[ENHANCEMENT] Saturation editor spectrum center. Allow change of center.
If one wants to play with orange/reds then we end up with something of a UI mess WRT the control points. They wrap the spectrum. This works but it is visual mess.
I note that the Color adjustment effect can draw a spectrum with a different center. Panning the spectrum. Support panning for this effect. Given the control points are likely tied to a hue degree value they could/should just come along for the ride and display properly.