Recent Doxygen vs our docs

[Benjamin Kosnik]

>Please keep this bit in, if you commit this patch.  (There's no way to
>add comments which won't be discarded by doxygen's rewriting, which is
>why this one is the onky such comment.)

I wasn't going to commit this patch.

:-)

The documentation bits are probably a good idea, however. I think the
update to the user.cfg.in file should wait till we've found a known good
version of doxygen, don't you think?

-benjamin