Ensure that folder protection is deactivated for the path of the base website when deleting a vhostsubdomain.

Bugfix: $app->system->unlink function had wrong parameter name, no files were deleted ever

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

Bugfix on db-Class (datalog Update)

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

Fixed (partly) FS#2310 - Template switch not working in mailuser module, for dashlets and the login page

- Added missing sys_tpl table to ispconfig3.sql and moved the definition of the table to the upd_0035.sql file as new tables cant be added in existing update files.
- added new ssl_key field to web_domain table.
- cleaned up unused code from apache plugin.

- install: touch auth.log
- login: write success/fail to auth.log
- cron: log rotation for auth.log

- Added new web folder named private to web folder layout. The folder is intended to store data that shall not be visible in the web directory, it is owned by the user of the web.
- Changed ownership of web root directory to root user in all security modes to prevent symlink attacks.
- Apache log files are now owned by user root.
- Improved functions in system library.

- Fixed: FS#2292 - monitor_tools.inc.php uses /var/vmail and not the mail directory specified in server config
- Changed code comment in login/index.php file.

Added wrappers for several base filesystem functions like rename, copy, chown, chgrp etc. to system lib.