GSColorspace

[Chad Hardin]

CUPS adds some extra concepts for colorspaces.

If GNUstep had knowledge of these it would help in mapping the 
colorspaces CUPS gets from PPD files into a GSColorSpace.

The ones I propose to add are:

GSDeviceCMY  (no K)
GSDeviceRGBK
GSDeviceN  (Palette, I suppose)

I'm just proposing to add these items to the GSColorSpace enum, nothing 
more.

These additions should not hurt anybody and may come in handy later.

Should I submit a patch for this or are there any objections?

Chad