Cycles: mist pass added, with start/depth/falloff control. If the pass is
enabled in a render layer a Mist Pass panel will be shown in the world
properties.

git-svn-id: https://svn.blender.org/svnroot/bf-blender/trunk/blender@57278 954f8c5b-7b00-dc11-b283-0030488c597c
Usablity:

Textbuttons: double click now selects entire words (like on file path segements)
Triple click was requested too, but that's not a WM event type yet.



git-svn-id: https://svn.blender.org/svnroot/bf-blender/trunk/blender@57280 954f8c5b-7b00-dc11-b283-0030488c597c
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
Cycles: ray visibility options now work for lamps and mesh lights, with and without
multiple importance sampling, so you can disable them for diffuse/glossy/transmission.

The Light Path node here is still weak and does not give this info. To make that
work we'd need to evaluate the shader multiple times which is slow and we can't
detect well enough when it is actually needed.

git-svn-id: https://svn.blender.org/svnroot/bf-blender/trunk/blender@57284 954f8c5b-7b00-dc11-b283-0030488c597c