Blender Git Loki

Move towards GPU-side tessellation

Currently only lands all the basics which are needed to
support using GPU tessellator from the OpenSubdiv library.

CPU evaluation is disabled in purposes of testing GPU side,
which means bounding box is wrong, edges are not displayed,
textured mode is likely also broken since now.

Data structures layout and API is not final at all, it is
just a cleaned version from the patch which i had last week.
All the drawing should be moved outside from the CCGSubSurf
structure and become some more generic functions in bf_gpu.

Also currently tessellation is hardcoded to use CUDA backend,
would either become an user preference or some automatic mode
in the future.

Wouldn't recommend using this state in the production, it's
still just a basis for further development and doing some
tests.