Attempt to fix #35665: disable correlated multi jitter sampling on the GPU for now,
seems to be giving issues with CUDA 4.2 but I can't figure out why exactly.

git-svn-id: https://svn.blender.org/svnroot/bf-blender/trunk/blender@57360 954f8c5b-7b00-dc11-b283-0030488c597c
Cycles lamp specials menu now includes separate X/Y size for area lamps
and strength (for the basic default node setup, this can't work with with
arbitrary nodes).

git-svn-id: https://svn.blender.org/svnroot/bf-blender/trunk/blender@57361 954f8c5b-7b00-dc11-b283-0030488c597c