[Xcb] OK, I lied; one more image library update

[Barton C Massey]

One last set of changes to the new image library.

After talking with Keithp last night, I realized that z
pixmaps with depth 1 but more than 1 bit-per-pixel were not
supported, and that indeed 1 bpp z pixmaps were not
supported properly at all.  So I made a slight change to the
image structure, and also a slight change to one API
function (and a whole bunch of internal changes, of course),
and now in theory it *should* all work, although it's never
been tested...

Also, I found and fixed my doxygen bug, and so the image
structure is now fully documented.

Also, I updated the popcount in aux/xcb_bitops.h with a
better version.  See
  http://wiki.cs.pdx.edu/bartforge/popcount 
for details.

BTW, nothing's certain yet, but it looks like there's a good
chance I'll be traveling to FOSDEM next February to talk
about XCB and X images.  Big fun if it works out.

Try my code.

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


    Bart