Decrease Color Slider Dancing further.

And the quest continues.

Errors still show up on darker colours, in particular blue causes the
saturation to go up. Makes perfect sense algorithm wise(there's less
possible colours at those lightnesses, so more chance at mistakes), but
not usuability wise and it's a pain to get rid of it.

Again to fix these errors I either jack up the precision of the
algorithms to long double, or I rewrite the whole color slider docker to
be more like the advanced colour selector. But both are very complex to
do.

BUG:313787
BUG:340751