Fixed color balance tool. Problem was: we pretended to do Lift/Gamma/Gain,
but in reality we did (1-Offset)/Power/Slope. (slightly modified ASC CDL).
So now, the GUI is able to switch modes between ASC CDL-mode and real
Lift/Gamma/Gain.
It also adds a switch to enable Neutral Black/White flipping
(very usefull for black point selection)
This closes:
[#18078] bugfix #18010 Sequencer lift