Root motion

This feature looks simple to implement, i may be wrong but i don't even know if there is already a ready solution for that.

1. We need to define a bone as the root bone (the one that moves the entire "armature");
2. Then, the transforms from animation must be neutralized (?) and returned as a vector;
2.1 The returned vector needs to be applicable as velocity, which i don't know exactly how it will works as the returned vector would be a static "location".

I can look into it in my vacation, if anyone has some suggestions let me know :+1:

No files, tests, or entry points are named. Start by locating the engine's armature and animation handling, then determine how a root bone should be defined and how its animation transform becomes usable velocity; done means those behaviors are specified and supported.

Written by the indexing model from the issue text.