CGM driver update

Dan,

If you wouldn't mind, I'd like review on the color mapping modernization 
patch I committed to the CGM driver:

  http://www.ghostscript.com/pipermail/gs-cvs/2003-October/003698.html

The whole idea of the code seems a little dubious, actually. Comments 
welcome.

There's another problem I'm stuck on: gs dies with '/undefined in get' 
which I use the cgm devices with tiger.eps or golfer.eps. It completes 
without error for alphabet.ps, waterfall.ps, colorcirc.ps, and 
escher.ps, so it seems to be related to eps parsing?

I also don't have a viewer for CGM files, so I can't verify it's 
producing correct images when it does complete. I'd appreciate is 
someone (Alex?) could verify that as well.

Cheers,
 -r