Recode the utility functions handling filenames using the Filename module
Add some utility functions
Copy a file in binary mode and covenience operators ((%) and (@@))
Remove the "/" in the filenames everywhere
We use the /^ operator now (Filename.concat) so we don't need a such hack
Add the possibility to specify custom exporters for source pages

An exporter is a command that takes in input a page with a given
extension, and outputs html to stdout.  It is now possible to specify
custom exporters by pages extensions (it can override the builtin
markdown parser).

Two example exporters are provided :

- a simple exporter that outputs input file, useful to embed some html
  in the template
- an exporter for .org files, using mlorg
  (http://kiwi.iuwt.fr/~asmanur/projets/mlorg/)
Bugfix: The links in the bar were not valid if the page was in a subdirectory
It's now fixed adding some ../
Oops. Remove the bash-ism in the ./configure script