BMO_ITER macros to make defining iterator
loops easier. Moved some files around.
And also made the editmesh conversion functions
tesselate ngons to triangle fans, since it's
more stable for conversion, and editmeshes are
never displayed to the user anyway. And ported
akey to bmesh.
Next up I plan on adding face iterators to DerivedMesh,
since that's the last major chunk of major refactoring
left, I think, except perhaps the uv editor (at the
moment it's probably close to working, but it's still
converting to editmeshes for everything, which is very
bad).
