METAL-COATED STRIP The present invention relates to metal-coated, steel strip. The present invention relates particularly but not exclusively to metal-coated, recovery annealed, and thereby high tensile strength, steel strip that is suitable for use as a paint line feed. The term "recovery-annealed" is understood herein to mean steel strip that hats been heat treated that the microstrueture undergoes recovery with minimal, if any, recrystallisation, with such recrystallisation being confined to localised areas such as at the edges of the strip. The present invention relates particularly but not exclusively to recovery annealed, and thereby- high tensile strength, steel strip that has a corrosion-resistant metal coating and can be painted and thereafter cold, formed (e.g. by roll forming) into an end-use product, such, as roofing products. The present invention relates particularly but not exclusively to recovery annealed, and thereby high tensile strength, steel strip that has a corrosion-resistant metal coating on the strip and a paint coating on the metal coating. The present invention relates particularly but not exclusively to a corrosion-resistant metal coating in the form of a aluminium/zinc alloy. The present invention relates particularly but not exclusively to metal-cosited, recovery annealed, and thereby high tensile strength, steel strip that is produced by a hot-dip coating method. In the conventional hot-dip metal coating method, steel strip generally passes through one or more heat treatment furnaces and thereafter into and through a bath of molten coating metal, such as an aluminium/zinc alloy, held in a coating pot. The furnaces may be arranged so that the strip travels horizontally through the furnaces. The furnaces may also be arranged so that the strip travels vertically through the furnaces and passes around a series of upper and lower guide rollers. The coating metal is usually maintained molten in the coating pot by the use of heating inductors. The strip usually exits the heat treatment furnaces via an outlet end section in the form of an elongated furnace exit chute or snout that dips into the bath. Within the bath the strip passes around one or more sink rolls and is taken upwardly out of the bath. After leaving the coating bath the strip passes through a coating thickness station, such as a gas knife or gas wiping station at which its coated surfaces are subjected to jets of wiping gas to control the thickness of the coating. The coated strip then passes through a cooling section and is subjected to forced cooling. The cooled strip thereafter passes successively through a skin pass rolling section (also known as a temper rolling section) and a tension levelling section. The skin pass rolled and levelled strip is coiled at a coiling station. The main purpose of conventional skin pass rolling strip is to condition the strip surface (with minimal thickness reduction) to smooth the surface. A smooth strip surface is important in order to produce a high quality painted surface on metal-coated strip. The main purpose of conventional tension levelling strip is to deform the strip so that it is sufficiently flat for subsequent processing, for example in a paint coating line operating at high speed (i.e. at least lOOxn/min) . The applicant has found that producing metal-coated steel strip, particularly recovery annealed, and thereby high tensile strength, steel strip with minimal residual stress, ie residual stress of no more than 100 MPa, makes it possible to consistently and reliably roll form the strip. This invention is an important invention from the viewpoint of being able to provide end users of strip, ie the roll-formers, with consistent quality strip. This invention is the subject of Australian complete application 43836/01 in the name of the applicant, In the context of the present invention, "residual stress" is understood to mean the residual stress through the thickness of the strip. Accordingly, references to "residual stress" herein should be understood as references to through-thickness residual stress. ' The applicant has also found that in order to produce strip with minimal residual stress it is necessary to skin pass roll and tension level under different conditions than were used previously, with the overall result that the strip is rolled relatively lightly. The applicant has also found that recovery annealed, and thereby high tensile strength, strip coated with an aluminium/zinc alloy that is produced under these relatively light rolling conditions is more susceptible to a particular type of surface defect than high tensile strength aluminium/zinc alloy-coated strip produced in conventional skin pass rolling and tension levelling conditions. The present invention is concerned with minimising this surface defect. There are 2 main types of the surface defect. Figures I/ 2a and 2b are photomicrographs of both types. Both types of the defect are caused by Zn and ZnO dust particles that are deposited on steel strip prior to applying a metal coating to the strip. The type of the defect shown in Figure 1 is a dent/depression/half buckle that has a comet-shape, with the head of the comet pointing in the forward direction of travel of the strip. Typically, the defect is 20-50mm wide and 50-150mm long. This defect is caused typically by Zn dust which deposits onto the strip prior to the strip passing through the molten metal coating bath. i The type of the defect shown in Figures 2 a and 2b is an area of rough coating with very small pinholes that have the appearance of narrow streaks. Typically the defect is 10-9Omm wide and 200-3000mm long and may be associated with a buckle. This defect is caused typically by an '"avalanche" of ZnO dust which deposits onto the strip prior to the strip passing through the molten metal coating bath. It is noted that the defect forms on strip that is subsequently processed by conventional skin pass rolling and tension levelling conditions. However, the defect or the appearance of the defect tends to be removed at least partially by subsequent conventional tension levelling of the skin-passed rolled strip. The defeat is undesirable from the viewpoint of the aesthetic appeal of the strip. Defective strip is generally scrapped - and this is costly and wasteful* the line In addition, the defect has an impact on speed of paint lines. Specifically, the defect makes it necessary to operate paint lines at lower speeds than would normally be the case in order to ensure proper coverage of the strip with paint. The applicant has also found that the Zn and ZnO dust particles tend to be the result of condensation of Zn vapour as Zn or ZnO particles onto cooler sections of the elongated furnace exit chute or snout of the heat treatment furnaces that is immediately upstream of the coating pot in the direction of movement of the strip and subsequent release of the condensed particles onto strip passing through the chute or snout at that time. The Zn vapour I originates from the coating pot. The applicant has also found that there is increased release of Zn or ZnO particles when there are changes in production line operating conditions/ particularly temperature, in the chute or snout and changes due to processing different grades of steel/ which destabilise and thereby result in release of particles from existing built-up layers of Zn/ZnO deposits on the walls of the chute. | i The present invention is based on the realisation that the formation of the surface defect from deposition of Zn or ZnO particles on recovery annealed/ and thereby high tensile strength/ strip passing through the elongated furnace exit chute or snout can be minimised by controlling the temperature in the chute or snout to be sufficiently high to minimise condensation of Zn vapour onto the walls of the chute or snout and/or to be substantially constant to minimise destabilisation of Zn/ZnO deposits on the walls of the chute or snout that could result in the release of already-deposited material onto strip passing through the outlet end section. In this context/ "minimal surface defects" is understood herein to mean that there is no more than 1 defect of the types shown in Figures 1 and 2 per 500 lineal meters of metal-coated steel strip. In addition, in this context, "substantially constant" is understood to mean a temperature vajriation of no more that 20°C. With the above in mind, according to the present invention there is provided a method of producing a metal-coated, recovery annealed, and thereby high tensile strength, steel strip which includes the steps of i successively passing the steel strip through a heat treatment furnace, a bath of molten coating metal, and a conditioning station, and: (a) heat treating the steel strip in the heat treatment furnace; (b) hot-dip metal coating the strip in the bath of molten coating metal and thereby forming a metal coating on the steel strip; and (c) conditioning the surface of the metal-coated steel strip at the conditioning station by smoothing the surface of the strip, and which method is characterised by controlling the temperature of an outlet end section of the heat treatment furnace to be (i) sufficiently high to minimise condensation of metal vapour in the outlet end section and/or (ii) substantially constant to minimise destabilisation of the metal/metal oxide deposits on the walls of the outlet end section that could release deposited material onto strip passing through the outlet end section. j According to the present invention there is also provided a method of producing a painted, metal-coated, recovery annealed, and thereby high tensile strength, steel strip which includes the steps of successively passing the steel strip through a heat treatment furnace, a bath of molten, coating metal, a conditioning station, arid a paint line andi (a) heat treating steel strip in the heat treatment furnace; (b) hot-dip metal coating the strip in the bath of molten coating metal and thereby forming a metal coating on the steel strip; I (c) conditioning the surface of the metal-coated steel strip at the conditioning station by smoothing the surface of the strip; and (d) forming a paint coating on the conditioned strip in the paint line, and which method is characterised by controlling the temperature of an outlet end section of the heat treatment furnace to be (i) sufficiently high to minimise condensation of metal vapour in the outlet end section and/or (ii) substantially constant to minimise the walls destabilisation of metal/metal oxide deposits on of the outlet end section that could release deposited material onto strip passing through the outlet end section. The temperature of the outlet end section of the heat treatment furnace may be kept sufficiently high by controlling the upstream operating conditions within the furnace . The temperature of the outlet end section of the heat treatment furnace may be kept substantially constant by controlling the upstream operating conditions within the furnace . Specifically, in a situation in which there is a need to change the heat treatment profile of strip in order to produce strip that has different mechanical properties to immediately preceding strip/ the method includes controlling the) heat treatment profile of the strip in one or more sections of the furnace that are upstream of the outlet end section to adjust the mechanical properties of the strip as required and without substantially changing the temperature in the outlet end section. j The temperature of the outlet end section of the heat treatment furnace may be kept sufficiently high by appropriate selection of insulation material for the outlet end section to minimise heat loss within the outlet end section. The temperature of the outlet end section of the heat treatment furnace may be kept substantially constant by appropriate selection of insulation material for the outlet end section to minimise heat loss within the outlet end section. Prefer-ably the metal of the metal coating is a j aluminium/zinc alloy and the metal/metal oxide deposits are Zn/ZnO deposits . Prefer-ably the aluminium/zinc alloy contains at least 30% by weight aluminium. Prefer-ably the method includes controlling the wall temperature of the outlet end section of the heat treatment furnace to be at least 450°C. Prefer-ably the method comprises controlling the wall temperature of the outlet end section of the heat treatment furnace to be at least 480°C, . Preferably the method includes controlling the wall temperature of the outlet end section of the heat treatment furnace to be with-in a temperature range of 40°C, more preferably 20°C. The furnace may be any suitable furnace, such as a horizontal furnace or a vertical furnace. Preferably the furnace has an elongated furnace exit chute or snout that extends into the bath. The term "high tensile strength" is understood j herein to mean that the tensile strength is at least 450 MPa.. More preferably the tensile strength of the steel strip is at least 500 NPa. Preferably step (c) of conditioning the steel strip produces residual stress of no more than 100 MPa in tho strip. Preferably, step (c) of conditioning steel strip produces residual stress of xio more than 90 MPa through the thickness of the strip. Preferably step (c) of conditioning the steel strip smoothes the surface of the steel strip so that it is suitable for painting in a paint line. Preferably step (c) of conditioning the steel strip smoothes the surface o£ the steel strip so that it is sufficiently smooth for painting in a paint line operating at least at 80% of its rated maximum production line speed. Preferably step (c) of conditioning steel strip maintains the strip sufficiently flat for painting in a paint line. The term "sufficiently flat" is understood herein in the context of complying with appropriate national standards, such as Class A and Class B flatness specified in Standard AS/NZ 1365. Preferably step (c) of conditioning the steel strip includes rolling the strip. The rolling conditions may be selected as required to condition the surface of the strip find to produce residual stress of no more than 100 MPai Preferably the rolling conditions are selected to | produce residual stress of no more than 60 HPa. More preferably tlie rolling conditions are selected to produce residual stress of no more than 50 MPa. More preferably tlie rolling conditions are selected to produce residual stress of no more than 30 MPa. Appropriate rolling control parameters include, by way of example/ any one or more of i (i) strip extension; (ii) roll force; (iii)roll bending; and (iv) entry and exit tension. Preferably the metal-coated steel strip has a thickness of no more than 1mm. More preferably the metal-coated steel strip has a thickness of no more than 0.6mm. According to the present inventd.cn there is also provided a metal-ooated, recovery annealed, and therefore high tensile strength, steel strip having a residual stress of no more than 1OO MPa and no more than 3. surface defect 1 of the types shown, in Figures 1 and 2 per 500 lineal meters of steel strip. Preferably the steel strip is coated with an aluminium/zinc alloy. Preferably the aluminium/zinc aXloy contains at least 30% by weigh.t aluminium. Preferably the tensile strength of the steel strip is at least 450 MPa. More preferably the tensile strength off the steel strip is at least 500 MPa. According to the present invention there is also Led, and provided a painted, metal-coated, recovery annea therefore high tensile strength, steel strip having a residual stress of no more than 100 MPa and no more than 1 surface defect of the type shown in Figures 1 and 2 per 500 lineal meters of strip. Preferably the steel strip is coated with an aluminium/zinc alloy. Preferably the aluminium/zinc alloy contains at least 30% by weigh.t aluminium. Preferably the tensile strength of the steel strip is at least 450 MPa. More preferably the tensile strength of the steel strip is at least 500 MPa. The present invention is described further by way of example with reference to the accompanying drawings of which t Figures 1 and 2 are photomicrographs of the 2 main types of the surface defect that the present invention is concerned with; and Figure 3 is a schematic drawing of one embodiment of a continuous production line for producing coated metal strip in accordance with the method of the present invention. With reference to Figure 3, in use, coils of cold rolled steel strip are uncoiled at an uncoiling station 1 and successive uncoiled lengths of strip are welded end to end by a -welder 2 and form a continuous length of strip. The strip is then passed successively through an accumulator .3, a strip cleaning section 4 and a furnace assembly 5. The furnace assembly 5 includes a preheater, a preheat reducing furnace, and a reducing furnace. The strip is heat treated in the furnace assembly 5 by careful control of process variables including: (i) the temperature profile in the furnaces, (ii) the reducing gas concentration in the furnaces, (iii) the gas flow rate through the furnaces, and (iv) strip residence time in the furnaces