Blender Git Loki

-> Beginning of Custom Data support for BMesh

Now that new allocator is in place, Custom Data
can be effeciently added to BMesh. The plan is to
make all data not directly related to topology
Custom Data and allow callers to decide precisely
what information a mesh should have in order to
make the best tradeoff between memory usage/speed.

Right now not much to look at, just some structure
definitions and commented out code. More to come
soon...