Hi all,

This patch addresses the problem of ambiguous conventions for the
placement of the title related macros (\author, \date,...) with
respect to the main document body in different latex classes. It
introduces the following changes:

* org-exp.el:
    - added the following options:
      - title-position (tpos)
      - with-title (wtitle)
      - with-author (wauth)
      - with-date (wdate)
      - with-maketitle (wmtitle)
    
* org-latex.el:
    - implemented handling of new options (see above):
      - title-position controls placement of \title, \author, \date;
        possible values are "b" = before \begin{document},
        any other values default to after \begin{document}
      - with-* controls if the corresponding macro is exported at all
        this can be convenient for more complex titles (e.g. several
        authors including affiliations,...)

The patch seems to work for me so far. What do you all think? IMO it
would be useful to integrate this, as it gives slightly more control
over the export process. Of course one might want to think about
better option names. The diff is done against commit
bc161ded3693f752616dcd247fc9d638789025ee.

Let me briefly describe my current use case:
I disable all commands except \title, use babel to created a title.tex
file (including several authors and affiliations) by tangling latex
code and then include the file (into the main body of the document,
not the preamble). That's the only decent way I've found to do this,
if anyone knows an easier way (I have the feeling that I might be
overlooking an obvious solution) please let me know!

Cheers
Sebastian