Code cleanup: avoid some warnings due to implicit uint/int/float/double conversion.

git-svn-id: https://svn.blender.org/svnroot/bf-blender/trunk/blender@57281 954f8c5b-7b00-dc11-b283-0030488c597c
Cycles: experimental correlated multi-jittered sampling pattern that can be used
instead of sobol. So far one doesn't seem to be consistently better or worse than
the other for the same number of samples but more testing is needed.

The random number generator itself is slower than sobol for most number of samples,
except 16, 64, 256, .. because they can be computed faster. This can probably be
optimized, but we can do that when/if this actually turns out to be useful.

Paper this implementation is based on:
http://graphics.pixar.com/library/MultiJitteredSampling/

Also includes some refactoring of RNG code, fixing a Sobol correlation issue with
the first BSDF and < 16 samples, skipping some unneeded RNG calls and using a
simpler unit square to unit disk function.

git-svn-id: https://svn.blender.org/svnroot/bf-blender/trunk/blender@57282 954f8c5b-7b00-dc11-b283-0030488c597c
Fix CUDA/OpenCL build after last commit.

git-svn-id: https://svn.blender.org/svnroot/bf-blender/trunk/blender@57283 954f8c5b-7b00-dc11-b283-0030488c597c