Add CMYK Color Space

[N-Upchurch]

https://drafts.csswg.org/css-color/#cmyk-colors

I think many web pros are failing to see the importance of this. Beyond ensuring proper color values for print styles, coming from a design background here, the ability to work in the CMYK color space is one of the final differentiators between FOSS and closed source, commercial graphic design software. This could be a huge step towards making FOSS software and Linux viable for design professionals.

[Schweinepriester]

Spec is probably https://drafts.csswg.org/css-color-5/ because

Moved @color-profile and device-cmyk to level 5 per CSSWG resolution

At least related to #1314 and #5958.

+1000 to what you wrote, though :)

[N-Upchurch]

Ah, put off again?! Love the inclusion of profiles though.