min/max ranges don't behave circularly as they should

[kotoroshinoto]

If say, I wanted to re-create the "roses" example on http://medialab.github.io/iwanthue/

I would need to use hmin 330 and hmax 20, and the function would need to know to use the "left" and "right" portions via the circularity of the color space.

At the moment, it just chokes on the min <= max arguments not being true.

It would also be acceptable to maintain the min/max requirements as such and have a boolean switch to indicate that the range was an exclusion rather than a selection.