Blender Git Loki

[note: do not test quite yet]

Phase 1 of restructuring done. There are now two
distinct subclass systems within the bmesh API;
one is compile-time, and forms the backend of what will
eventually be a "lite" bmesh API for modifiers (the
ones that use bmesh are simply too slow right now).
The other is dynamic, and will be used to implement
multires reprojection.

The idea was to solve as many serious problems with
memory, speed, etc, at once as possible and set up others
to be solved more easily later.

I've also added holes into the data structure, but not
the api; I don't plan to finish implementing that until
after bmesh gets into trunk. I simply wanted to lessen
how much code I'll have to rewrite, since I was doing a
fairly major restructuring anyway.

In addition, I've added iteration support to mempool, to
avoid having to store linked list pointers (though this
has caveats).

Next step: merge in trunk changes. . .oh, what fun :P