Add hwb() + fix max for hue

Following

harthur/color-string#8
harthur/color-convert#10

+

capping must be done before convert loop for each spaces.
Otherwise it’s not coherent with how color-convert handle overflow
(modulo).

Ref #24
Can't do that. Like I said, it currently create a bug due to how color-convert transform 360 to 0.
So you can have hsl channel to hue = 0 & hwb channel set to 360. Seems not coherent to me.