Added new theme. You now can change between 64px size icons, 32px size icons (the default-value) and no icons

Added a new theme called no_navimg. This template removes the icons from the top-Navigation if you don't like them

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!

Fixed: FS#655 - Resolution problem 12024x768 Px in Backend

- Updated Logo in default theme.

- Formatted error messages for better visibility.