Fix random crashes when converting image color space

The patch basically ports image color space conversion into strokes
system. The crash happened becasue updates were initiated right when
the visitor was changing layers. With the strokes, this problem should
be resolved.

The patch also changed UIX: now 'Image->Properties->Color Space'
changes the entire color space of the image, but not only color space
of the root node (projection).

BUG:410776