Merge pull request #609 from jeremygray/master

BF, TESTS: fix and simplify visual.BufferImageStim, add tests
Merge pull request #610 from jeremygray/master

TESTS: higher crit for test_bufferimage
ENH: setGammaRamp can now cope with 256x3 or 3x256
ENH: work on BitsSharp integration. Checks and loads/save identityLUT on init
BF: If the BitsSharp is not found don't try to get its info
DEMO: add script to assist scoring IAT from within Coder