Completly same functionality as VHost-Subdomain, not to disable if already existing vhostalias-somains in system.

http://bugtracker.ispconfig.org/index.php?do=details&task_id=1689

Added a new module called "domain". With this module you can manage all domains (web + mail). Per default this module is not active. To activate it, you have to change the System Interface Config -> domains -> use the domain module. You also have to activate the domain-module for the admin (and for every client if you want). Important: you can not use this module if you have reseller!

- Formatted error messages for better visibility.