Add support for Pantone swatches

[thisandagain]

http://goffgrafix.com/pantone-rgb-100.php

[thisandagain]

If we are looking for color systems that are widely used, you don't get much more common than PMS swatches. This is something that I would actually get some use out of regularly.

[dblock]

👍

https://www.pantone.com is the official reference.