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
c4ef2e2f2e