feat(color): add FromStr implementation for Color

[Mehrbod2002]

fixes: #143

[joshka]

There's a note in the issue about whether we should / shouldn't bring in a new dependency for this (it seems like a fairly small amount of code to avoid doing so). I could go either way, but lean towards not bringing it in. Do we gain anything by putting the implementation off onto colorsys?

[sophacles]

Code looks good to me.

Would like to see documentation - its non-obvious how to make Indexed and Rgb from a string without reading the code.

[orhun]

I think we should also add unit tests for this.

[Mehrbod2002]

I think we should also add unit tests for this.

The tests added

[joshka]

Nice work. This looks good to me.

I thought of some edge cases

[sophacles]

There's some edge cases that we probably want to deal with.

[orhun]

Neat.