Fix ReplaceInkProcessing to work correctly with transparent colors (fix #435)

Now we can replace a solid color with transparent in RGBA and Grayscale
images.
Fix problems with multiple editors in MovingPixelsState (fix #419)
Fix #392 - Crash when another monitor is plugged in

When we change the number of monitors, we've to restore the primary
DirectDraw surface, but it cannot be just "restored", it must be
re-created.

Note: probably the real fix for #436 too
Merge branch '1.0'

Conflicts:
	src/app/color_utils.cpp
	src/app/tools/ink_processing.h