Blender Git Loki

OpenGL: manage built-in shaders better

As our library of built-in shaders grows, it's important to create, access, and discard them efficiently.

Lookup via GPU_shader_get_builtin is now constant time instead of linear (# of built-in shaders). This is called very often with our new immediate mode.

Creation and discard are unified.

Adding a new shader requires fewer steps.

365 lines shorter :D