Move PointIndexGrid tools into GU_VDBPointTools

Conflicts:

	openvdb_houdini/houdini/geometry.h
SESI_OPENVDB also might not have OPENVDB_HOUDINI_API
Override updateParmsFlags() in Morph Level Set
Fix bad comment merge
Merge pull request #30 from sideeffects/send_upstream

New changes from Houdini trunk (GU_VDBPointTools)
various improvements
fixed mesh simplification bug
Blosc compression
minor updates
Merge remote-tracking branch 'upstream/master'

Did *NOT* include any changes for SOP_OpenVDB_Convert.cc

Conflicts:
	openvdb/Makefile
	openvdb_houdini/Makefile
	openvdb_houdini/houdini/GU_VDBPointTools.cc
	openvdb_houdini/houdini/SOP_OpenVDB_Morph_Level_Set.cc
	openvdb_houdini/houdini/geometry.h