Front-office : part 4

- Fixed a major bug on AJAX scripts. However, the second part of
scriptLoadArticles still need to be fixed.
- Deleted expositions.php. Irrelevant.
- Added jquery support on some pages
- Changed the link.php to connect to a local database
- Fixed a bug in add_text.php which added the text with a wrong date
-  Corrected some CSS and visual errors (remnants from stf's galanthis)
on entete.php, articles.php, index.php, contact.php, liens.php...