Blender Git Loki

Fix T39627

HSL sliders jumping. The issue here is that we store HSV in display
space.
To correctly account for that, made sure HSV/HSL is now using the
displayed
color to compute the values in the sliders. RGB values still show
the property values (linear for linear, gamma corrected for gamma
corrected)

We could change the way we store HSV uniformly (ie in all the code), but
we would need to add many more conversions in the picker code to account
for storing it that way. Also it doesn't make sense: Color pickers
should help with -visible- color selection. It may
be worth changing the RGB sliders as well.
My fix takes into account the way HSV is stored in HSVCube as well in
the code.