Updating the GNU ELPA package of AucTeX

[Stefan Monnier <monnier@iro.umontreal.ca>]

The GNU ELPA package of AucTeX is ridiculously old.

As part of updating, I'd like to "streamline" the process, which mostly
involves reducing the difference between the code in the `elpa' branch
and the code in the official auctex repository.

The differences I can see are the following:
- the `preview' sub directory (in `elpa' there's no such directory, all
  the files within it are either removed or moved up one level).
- the .dtx vs .sty files.
- the .texi vs .info files.
- the Makefile.in, configure.ac, and friends.

Ideally, I'd like the GNU ELPA package to be built directly from the
source code (currently it seems it's made from the tarball instead,
IIUC).  But contrary to the XEmacs case, the construction of the GNU
ELPA package is made by a very simplistic process (which does very
little more than create an auctex-autoloads.el file, and tar-up the
result).  I can make this process more sophisticated, but since it's run
fully automatically, I'd very much prefer not having to run code from
the package itself.

IOW, it's easy to arrange the construction so as not to include some
files (e.g. Makefile.in).  It's also possible (but I'm not very eager to
do it) to rename files during construction.  But I really would not want
to extract the sty from the dtx during construction.

So, the real problems are:

* Preview subdir:

  I see two clean and easy ways to deal with:
  - Split it (again) from AucTeX.
  - "mv preview/* ./; rmdir preview"
  Is one of those two options agreeable to you?

* The .texi files:

  The problem is not specific to auctex, so I'll have to come up with
  a solution anyway, probably building the .info files during
  construction of the ELPA package.

* The .dtx files:

  Here, building the .sty during construction of the ELPA package is
  not really an option.  So I see the following ways out:
  - Include the generated .sty file in the `elpa' branch (with the
    usual problems associated with VCS control of auto-generated files).
  - Build the .sty when *installing* the package (when package.el
    installs a package, it does various things additionally to unpacking
    the tarball, and it could be made to run tex as well).
  - Build the .sty lazily just before the user needs it.
  Does one of those options sound good to you?


-- Stefan