* Quarantine section:
- Added quarantine evolution graph for amavisd-new, mailscanner and qmailscanner.
- Fixed a bug in mailscanner statistics.
- Optimized pagination processing time for quarantine results.
- Page load enhancement by caching statistics data. Also added a button to force statistics processing.

* Dependencies:
- Added dependencie on GD and GD::Graph::lines Perl modules.

Yeah, I know I have added a new functionnality during a RC cycle... Bou! :-)