FS#2700 - Delete Addon Package: Invalid ID

- Merged language files.

- Adde some missing strings to translations in faq module.

- Bugfix: sys.ini and server.ini: if checkbox is not checked, write default value from tform file into database.

- New feature: you can now add directive snippets for Apache, nginx, and PHP under System > Directive Snippets. These snippets are then available on the Options tab of a web site where they can be easily added to the respective textarea by simply clicking the name of the directive snippet.

Note to all contributors: please use utf-8 encoding in files!

Fixed: password match function blocked tabs incorrectly
Fixed: set focus on username input field threw an error if this field did not exist on a page

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

Corrected paths in main tpl

- Added overtraffic notifications to traffic quota system (part of FS#2059 - Extend Traffic quota system)