This commit removes the experimental CUDA kernel, making SSS and CMJ
regular features.
Several improvements have been made in the past few
weeks (thanks Sergey!) which make SSS render several times faster (2-3x
compared to 2.76b) on the GPU, and the increased VRAM usage has also been
fixed. Therefore the experimental kernel is no longer needed.
Differential Revision: https://developer.blender.org/D1726
Manual has been updated: too:
https://www.blender.org/manual/render/cycles/features.html