Interactive color distance flood fill first version.
Fix some settings being wrong according to GUI on another image load.
Some (incomplete) performance improvement.
Replicate another bit of selection behavior from SAI.
Remove debug code.
Add tooltip about current floodfill state, make it more usable.
+ Merge all temporary buffers into one to spare some memory.
Some selection/transform/floodfill optimizations.
Fix bug with undo.
Add "Zoom..." action. Fix floodfill bug with zoom.