* better type safety for BM_elem_flag_* and BM_elem_index_* functions.
* add BMElem type to be used where BMFace/Edge/Vert/Loop can be interchanged.
* fix bug in select manifold, found when making functions more strict.
* added BM_elem_flag_set, BMO_elem_flag_set. to avoid 'if(...) enable(); else disable();' all over the place.
* added bmesh_operator_api_inline.c, the header file was getting messy.
* 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.