* PBVH can now be created contain both from face grids or standard
meshes. The former is much quicker to build for high res meshes.
* Moved some drawing code into pbvh (mostly for the frustum test).
* Moved ray intersection code into pbvh.
* GPU buffers also can be built from either mesh or grids now.
* Updated sculpt code to work with this. The ugly part is that there
is now a macro for iterating over vertices, to handle both cases,
and some duplicated code for e.g. undo.
* Smooth brush does not work yet with grids.
* Convert all code to use new functions.
* Branch maintainers may want to skip this commit, and run this
conversion script instead, if they use a lot of math functions
in new code:
http://www.pasteall.org/9052/python
* Fix slowdown/freeze entering editmode on a high poly mesh,
dm->getNumFaces can be slow, don't call it in a loop.
* Fix 64bit pointer casting warnings.
