Changes

A new array attribute, '''''steerable_axle[]''''', was added to [[Documentation/Engine/Units/accessory_chassis_data|chassis data]]. It controls which axles are steerable instead of locator names. Locator names now define only the wheel type (model) dependency. The semantics of '''''steerable_axle[]''''' is are the same as '''''powered_axle[]''''' or '''''liftable_axle[]'''''. If not defined, the values are inferred from the vehicle type. By default, a trailer will have no steerable axles and a truck will have its first axle steerable).