Blender Git Loki

Make OpenSubdiv working on a low-end video cards

This commit changes the way how mesh is being displayed when
using OpenSubdiv backend. It does no longer use neither effect
factories nor fragment shaders in order to make all the shaders
compatible with at least GLSL 1.3 compatible cards.

In fact, seems the shaders now goes down to GLSL 1.1 even.

Apart from this now the first material from the material stack
is used for colors.

Still requires our own OpenSubdiv branch:
https://github.com/Nazg-Gul/OpenSubdiv/tree/cuda-dynload

(it actually needs updated version of this branch)