Implemented:  FS#2388 - Optional confirm window on changing tabs

Bugfix: Show error message on smtp enabled without administrator mail / name

- Fixed missing templates and language entries
- Previous subdomain mode can be used concurrently
- Changed log path to a more convenient location

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

Using these variables in welcome email from admin, when mailbox is created.

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.