Can view niff, sunraster, gif, jpeg, tiff, fbm, cmuraster, pbm, faces, rle,
xwd, vff, mcidas, vicar, pcx, gem, macpaint, xpm and xbm files.  Can view
images, put them on the root window, or dump them.  Does a variety of
processing, including: clipping, dithering, depth reduction, zoom,
brightening/darkening and merging.
