IDEA make a dedicated three.js interface instead of supporting it

[gsimone]

This would introduce an entry point maath/three with functions such as:

1. convert buffers to Vector3 and back
2. convert matrics to three's
3. host the methods that currently depend on threejs, maybe keeping the same structure (this is currently the case for whatever needs quaternions and some matrix math.)
   3. might even be worth it just forking three's quaternions and matrices (maybe make them static instead of class based)