Hi all,

Just a small patch that might make life easier for
LaTeX (and esp. tikz) users.  It enables the output of graphics in a
lot of formats using imagemagick.  See below for an example.

This is my first patch, I have never programmed emacs lisp before, and
my common lisp experiences have been short and a while ago.  So please
excuse a (possibly) bad patch.

Details:
LaTeX source blocks now have three new options:
- :imagemagick
  When not nil the source block is processed to pdf and the pdf is
  converted with imagemagick to whatever is given as :file
  Thus, the format is not limited to png.
- :iminoptions
  This is passed to imagemagick before the pdf file
- :imoutoptions
  This is passed to imagemagick before the output file

Small Example:
#+begin_src latex ... :file test.jpg :imagemagick yes :iminoptions
-density 300 :imoutoptions -geometry 400 ...
will use this command for conversion:
convert -density 300 <tmp-pdf> -geometry 400 test.jpg

Full example:
Export this to pdf and to html to see the effect.
=======================================
* Test
  #+begin_src R :session :exports both :results silent
    library("tikzDevice")
  #+end_src

  #+srcname: test_plot
  #+begin_src R :session :exports code :results output latex
    tikz(console=TRUE, width=4, height=4)
    plot(rnorm(100), rnorm(100))
    dummy <- dev.off()
  #+end_src

  #+srcname: test_plot_png
  #+begin_src latex :exports (if (and (boundp 'backend) (eq backend
'latex)) "none" "results") :file test.png :imagemagick yes :iminoptions
-density 600 :imoutoptions -geometry 400 :fit yes :noweb yes :headers
'("\\usepackage{tikz}")
    <<test_plot()>>
  #+end_src

  #+srcname: test_plot_tikz
  #+begin_src latex :noweb yes
    <<test_plot()>>
  #+end_src

* Latex Options                               :noexport:
#+LATEX_HEADER: \usepackage{tikz}
=======================================

Regards,
Andreas