Document `getAll()` and `setAll()`

[svgeesus]

Thanks for explaining getAll() and setAll() and providing an example. The online docs don't cover those functions. That solves my problem. Given your understandable lack of enthusiasm, I'll close this PR.

Is there an other way or place to ask questions before submitting a PR? I was looking for a way to set a Color instance's coordinates using a string, they way you can when you instantiate a Color. Is there a way to do that via some subset of the parse() function? The idea is to workaround new Color() because this is a library with no dependencies (like Color.js). I am working around it with new colorInstance.constructor() and passing in the string that way. But if there's a setAll() that parses already I'd love to know about it.

Thanks!

Originally posted by @sidewayss in #460 (comment)

[svgeesus]

Dup of #463