testdiff now looks for "IMAGE_COLOR_TOLERANCE: Tol" statements in log
to execute diffimage with -toleranceOfColor Tol parameter.
Image difference is first performed with 0 tolerance and then optionally with non-zero tolerance,
so that the log always includes information that some images are different,
but with two different messages:
- "IMAGE differs" for images failed comparison;
- "IMAGE is similar" for images passed comparison only with non-zero tolerance.
v3d/materials - disabled MSAA and removed duplicate.
demo/samples/materials - compare screenshots with 0.8% color tolerance (2/255).
