[FR] Animatable Bone Transparency #176

Is your feature request related to a problem? Please describe.
Currently the only way to animate the transparency of a bone is by making many versions of a texture with different opacity's and then setting them as variants, which is a very unpleasant way of doing this.

Describe the solution you'd like
I would like to be able to animate the opacity of bones in Blockbench. Then when the animation is exported, all the necessary texture variants are generated and automatically handled.

Describe alternatives you've considered
I've considered doing it manually, which is obviously not a good experience, or using shaders, which are confusing and don't really fit in with how Animated Java works entirely without shaders.