add BM_ITER_MESH_MUTABLE which steps before entering the for() loop body and prevents the assert from complaining about removing mesh data while iterating as well as the crash.
this was done in quite a few areas, more may turn up.
patch by Nicholas Bishop, modified to avoid looping over vert-loops one extra time.
added BM_iter_as_arrayN(), returns an iterator as an array without knowing the length before calling.
* made bmesh_structure.h function names more consistant.
* remove unused code in bmesh_structure.c
* removed 'Edge Flip' operator (missing from bmesh but looked into trunk feature and dont think its worth keeping).
* tagged some BMESH_TODO's
* remove 'select' and 'hide' from BMLoop
* remove BMesh.update
* add BMesh.normal_update(skip_hidden=False)
* add BMElemSet.index_update(), eg: bm.verts.index_update()
bmesh api
* BM_mesh_normals_update() now takes skip_hidden as an argument
(previously this was default behavior), however this isnt good when
using BMesh modifiers, where you want all normals to be recalculated.
* add bm_iter_itype_htype_map[], to get the iter type from a BMesh
iterator.
* BM_vert_in_face now loops over a vert's faces rather then every vert in the face.
* rename bmesh_radial_find_first_facevert --> bmesh_radial_find_first_faceloop
* rename bmesh_radial_find_next_facevert --> bmesh_radial_find_next_faceloop
* rename BM_vert_collapse_edges --> BM_vert_collapse_edge (only collapses one)
