Max is 359deg for hue, since 360deg == 0deg

Also, capping must be done before convert loop for each spaces.
Otherwise it’s not coherent with how color-convert handle overflow
(modulo).

Ref #24
Add hwb()

Following

https://github.com/harthur/color-string/pull/8
https://github.com/harthur/color-convert/pull/10