* FAQ is now in English and Spanish. The two languages are in the same
XML file. Xsltproc can extract one language to produce a Docbook XML
file (with doc/common/multilanguage.xsl), than can then be compiled by
jade.

* Converted VLS user guide from LinuxDoc to Docbook XML.

* Updated the web site for those changes.

TODO :
- re-read VLS user guide : layout and language.
- do a better Makefile for the faq.
- translate the FAQ in French ?
- start to build the infrastructure to have the other docs in multilanguage ?