[cmm] Make scaling of objects possible through GUI

[Ithamar]

At the moment, imported models from Primal Prey and Cityscape are upscaled 32x. This is so their animation data can be safely converted to Classic Carnivores (which stores the vertices for animation in 16-bit signed integers, basically the floating point values * 16).

This should really be configurable, and even done if there's no need (from a technical perspective), but the user just wants to resize the model.