[Suggestion] Add - setboneBrightness{} mechanic

Modifying the brightness of model engine mobs/entities would allow essentially setting models as emissive.

- setBoneBrightness{mid=<modelID>;pid=<partID>;brightness=<0-15>} @self

where specifying only a model would set the brightness of all display entities within the model, and specifying a bone would set the brightness for only that specific bone.

Would be incredibly helpful. Thanks!