Blender Git Loki

Cycles: Added volume support for embree

Cycles: Embree support for ribbon line segments and subsurface scattering

Cycles: Embree accelerator now supports instanced triangle meshes

Cycles: more work on embree integration - triangle meshes now support deformation motion blur

Cycles: Progress with embree integration, still incomplete however

Cycles: Laid some foundation for embree ray accelerator: flags, UI and CMake