@dircategory entries sync'ed with info/dir

[Eli Zaretskii <eliz@gnu.org>]

I've committed to the emacs-23 branch changes in almost all of the
manuals in doc/misc that synchronize their @dircategory directives
with the corresponding entries in the info/dir top-level menu.  This
is so running install-info on the Emacs Info files does not cause
duplicate entries in the menu created by the Info readers from all the
`dir' files it finds on INFOPATH.

Some of the manuals' master copies are maintained outside of the Emacs
repository.  I tried to CC all of them here.  Please, when merging
future versions into the Emacs repository, be extra careful so as not
to lose these changes.  Ideally, you should sync your master copies
with these changes now.  Thanks in advance.

There's one problem left in this area that I'm unsure what to do
about, if at all.  The @dircategory directive of info.texi says
"Texinfo documentation system", and I believe it is maintained as part
of the Texinfo package.  The info/dir file that comes with Emacs puts
the corresponding menu entry at the very beginning (so that Info
newbies could see it), with no category at all.  OTOH, changing the
@dircategory for info.texi would be frowned upon by the Texinfo
maintainers.  So I didn't change it for now.

Karl, any suggestions?

Personally, I tend to think we could leave it alone: if someone runs
install-info on the Emacs Info manuals, she probably already has the
Texinfo manuals installed anyway, so the entry for `info' will end up
in that part, which is okay.