add facility to export tex project into a single, cleaned up .tex file

[stefan]

Hello Jörg. Here's a thing that I wanted so often,
and solved by some Haskell program (long ago):
when submitting a paper (final version) to a conference,
they want LaTeX sources - but I want them cleaned up.
So my program does:
* expand all \input (so the result is a single file)
* remove all % comments
* remove all \reminder{..}
and what it should do:
* compile the exported tex source and compare the result (pdf)
with my working version (should be identical).

[stefan]

This function should create a single .tex file that contains all included .tex files as well as the .bib file (see script  http://www.ccrnp.ncifcrf.gov/~toms/ftp/replacebib to insert a .bib file into a .tex file).