* 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.