GeglColorSpace is broken into two parts, GeglColorSpace and GeglColorSpaceImp.

The GeglColorSpace header is already in cvs.  The only ambigious part (I
think) is the limits field of the object.  The limits should define what
the upper and lower bounds of each color is.

The varients describe color spaces in a very specific way.  A varient of a
color space can be created with scales and rotations only.  If there is a
parity change, or a different orthagonal set (rectangular, polar, etc),
then it belongs to a different varient.

What this means is that any color space in which the same math produces
similar (though not exactly the same) results, then they are the same
varient.  This means that Lab and xyY are similar, HSV, and HSL are similar
(though HSL is much better defined) all RGB colors space are the same, and
all CYMK color spaces are the same.  The varient names could probably be
named better.  Perhaps after what their axies mean.  Many people call this
a photometric interpretation.