Various updates?

[danburzo]

I am working on a color library that aims to support all the CSS Color Level 4 formats, and would love to contribute to d3-color with some updates:

• HEX 4 and 8 formats
• RGB(A) and HSL(A) current syntax (rgb(255 255 255 / 0.1), etc.)

And could add HSV and HSI color spaces.

(+ more as I sort them out)

I was wondering which of these are in the scope of d3-color and whether I can submit PRs.

Thanks!

[danburzo]

(Closed in favor of #44)