xpm loader and colormaps

["Matthias Clasen" <matthiasc poet de>]

The current xpm loader doesn't try very hard to extract useful
information from the xpm colormap, eg xpms containing only a 
monochrome colormap will come out all black. I've rewritten
xpm_extract_color to try a bit harder. The replacement works
much better for xpms with monochrome, grey or multiple colormaps.

You can find it in

http://bugzilla.gnome.org/showattachment.cgi?attach_id=5045

Matthias