Providing extra information for Info menu generation

[Gavin Smith]

I know we probably have more ideas for projects in texi2any than we
really have time to implement just now, but one thing that I think
would be really nice is to allow complete omission of Info menus from
Texinfo source, without anything being lost.

Although generation of menus is already possible, as far as I know
most manuals and nodes do still use explicit menus.  This may be for
the benefit of Info output, where extra descriptive text can be given
for a node reference.

For example, in the main menu in the bash manual:

* Job Control::                 What job control is and how Bash allows you
                                to use it.

In the Texinfo source, this node could be defined like

@node Job Control
@nodeelaboration What job control is and how Bash allows you to use it.

I remember seeing a similar proposal before in a discussion one of
the GNU mailing lists (emacs-devel?); however, I cannot remember
where I saw it, so can't give due credit.

This would really clean up the syntax of Texinfo files, avoiding the
hetergeneous syntax implicit in the name "TeX-Info".  The special
characters would be @, { and } and that would be it, pretty much.

We could take this idea a bit further and allow arbitrary
cross-references from nodes that would appear in Info menus, as
a kind of "see also" link for the node.  This would enable the
generation of non-hierarchical manuals as a collection of nodes.
(This may not be as useful, though.)