Add tuple and non-alpha variants of methods

[ShayBox]

This is a continuation of #19

Also adds the HSLA lighten and darken methods.

[ShayBox]

This would be a good improvement to the library, an argument could be made that it's verbose and unnecessary, but what else is this library for than to convert data formats from one to another for other libraries, having to convert an array to a tuple, and/or strip off the alpha to make it work with the needed signature defeats the purpose of using this library, one could handle it entirely themselves at that point.

This is a breaking change because it re-introduces to_lab and to_lch, but as non-alpha variants instead, so would need to wait until v0.8

[mazznoer]

If you could make another PR with just to_rgb8() and to_rgb16(), I'll accept that.