Color manipulation in HSV space

[maufl]

Hey,

I just discovered the brighter and darker color methods. In general I really like having color manipulation methods, but it's not completely clear to me how they work. I usually like manipulating colors in the HSV space, for example to decrease the saturation.
I think it would be a good idea to have methods for this in the language :) Or maybe even better make it possible to define custom functions and access color channels.

Cheers