Updated the Debian installation instructions.

- Updated ToDo list.

Updated ToDo item list.

Moved server modules and plugins to new directory and updated the installer to create the symlinks for the modules and plugins from *-available to *-enabled directory.
Fixed a typo in mailfilter template.

Added a server module for clients and a mail plugin.

- Add some functionallity to MySQL class

- added a daily cronjob for stats creation in the installer.
- Fixed a bug in the spamfilter white / blacklist forms (thanks to satommy for reporting this)
- fixed ssl cert path in vhost templates/web_domain_ssl.htm
- fixed a bug in the apache plugin which prevented the copying of the standard error and index files.

Updated apache ssl cert creation.

- improved several functions in site module
- added server classes to restart services