This reorganizes the cloth UI, and changes some of the behaviour to be more reasonable. Changes included here: * Reorganized cloth panels * Improved some tooltips * Removed `vel_damping` option * Removed cloth pinning checkbox * Removed stiffness scaling checkbox * Separated shrinking from sewing * Separated self collisions from object collisions Reviewed By: brecht Differential Revision: http://developer.blender.org/D3691