* Now support a Surface mode next to the existing Volume mode. This binds
the mesh to the cage mesh surface rather than it's volume.
* Implemented reusing the bone heat weighting code.
* Advantage is that it works for cage meshes that are not volumes and that
binding is much faster.
* Weak point is that disconnected components of a mesh are not guaranteed
to stick together (same problem exists with bone heat weighting).
* Bind weights could still be compressed better to use less memory.
Example file:
http://download.blender.org/ftp/incoming/cloth_mdef_surface.blend
c4933cccfa