Figure out a way to constrain or bias color wheel

[sfoster]

I think it would be nice to be able to constrain the color picker to e.g. an autumnal palette, or predominantly greens or blues for an underwater vibe. We currently just use the full 360 degrees of the HSL color space and directly map the angle to hue, but could presumably put a function in front of that to produce different results given an angle.

[gandalf3]

Perhaps we could consider drawing the gradient with a canvas or something like that, if we want to change it on the fly?

[sfoster]

I am already doing that actually, I ended up not using the graphic we demoed with. See the renderColorWheel function: spectrum-client/htdocs/assets/colorwheel.js#L36