* 2D image painting support for masking to limit the max contribution of a stroke
to a pixel, to get it working compatible with projection painting. Not strictly
a bugfix, but the inconsistency here was annoying.
* Fix python errors in Texture Mask panel in image editor, was missing overlay
options.
* Clamp paint mask to 0..1 in case some texture exceeds it, this could give black
pixels due to integer overflow.
63f05576b8