Add Prototype/SpiderVehicle::color

[Schallfalke]

May I request to add "color" property to the prototype definition Prototype/SpiderVehicle?
It is useful to Spidertron, as its color mechanism is more like locomotives (selection) instead of cars/tanks (driver color).
Similar property already exist on Prototype/RollingStock, like here. So I wonder if the same should apply on Prototype/SpiderVehicle?

Use case: Different preset color (instead of the same brown) for different classes of modded Spidertrons.