Faceshift support, restructure, key reduction

- Added faceshift BVH support where we map Faceshift’s 0-90 degree
rotation to a 0-1 Z-scale on each blendshape-related joint, making it
easier to rig.

Added an option to call modo’s key reduction. This is called only for
the items created by the BVH import process.

- Updated to a kit structure.