Front-office : part 4 & ending unit tests

- Fixed several bug on every pages commited (most of all, remnants from
old website, wrong variables...)
- AJAX articles loading is now over.
- serie.php and index.php are now functionning.
- upgraded the form2 to delete the temporary preview image

Please BE AWARE that the deleting formulas aren't server-tested. PLEASE
TRY IT BEFORE GIVING THE KEYS.