[Xcb] Done with util/image for now

[Barton C Massey]

I think I've done about everything I really want to do with
xcb/util/image.  It seems to work on test cases, and seems
to me like it should be easily maintainable and portable.
The documentation seems to be there.  (Does some Doxygen
guru know why not all the members of xcb_image_t are being
documented?  I tried.)

Check it out, use it, have fun with it.  I did.

  git://people.freedesktop.org/~bart/git/util.git

    Bart