Munsell color system

[Ogeon]

The Munsell color system may be an interesting addition from a more artistic point of view. RIT provides some data files that may be used to convert from Munsell to xyY, but I haven't found any clear terms of use for those, but the colors themselves are not copyrighted and it looks like it's under a section of free-to-use stuff. That will need more investigation, since we must consider possible commercial use of this library.

Embedding a Munsell database into the library may be quite a bit of bloat, so this should probably be included as an opt-in feature.