Blender Git Loki

Implemented mesh shape key compression

Mesh shape keys are now compressed on file write by storing only the vertices that have changed from the rest position (the logic automatically determines if there will be a gain from such compression, if not, no compression will happen).

This showed 3x disk space reduction on Elizabeth's head here (4.5 kvert mesh, 157 shape keys for different facial expression):
http://dl.dropboxusercontent.com/u/91422001/liz_headonly_masterbranch.blend
http://cs617325.vk.me/v617325382/e0e1/cjnMXhbtU44.jpg

A User Preference (on File tab) has been added to save the shape keys in the old format (compressed shape keys won't be readable from Master branch)

This also decreases object mode undo memory usage, as undo uses a file in memory.

TODO: endian conversions won't work on compressed keys right now.