Blender Git Loki

py/api registration:
move calls to the classes register/unregister function into register_class() / unregister_class() and add docs.

also other minor changes:
- remove face sorting keybinding, was Ctrl+Alt+F, this is quite and obscure feature and face order normally doesn't matter, so access from Face menu is enough.
- add commented out call to mesh.validate() in addon template since its useful to correct incomplete meshes during development.