Added additional database options when default host goes down.
Revert "Added additional database options when default host goes down."

This reverts commit a1f4c68cc4bfdfd98c9277aabf1dc611ea7a0d58.
Added multiple MySQL database option in case the default goes down.
Core/Feature: Added a thread tracker
Core/Feature: The thread tracker works now also for nodes
Bugfix: Fixed #16
And a little cleanup
Layout/Installation: Updated the system check
Admin/Feature: Added a auto update function

This is not final and it needs some translations and corections. Will do it the next days
Bugfix: Fixed a bug where Iko crashed because of a bug of php
Bugfix: Just a little test bug fix.

@jtPox Please tell me what you wanted to do here so I can fix it correctly
Core/Language Pack: Updated the German language package
Core/Feature: Added a media BBCode for YouTube, Vimeo and Twitch
Core/Feature: Changed the sytax highlighter
Bugfix: Readded some deletions of the last commit
Correction: Corrected a bugfix in a59aa8696c2f018c644a2bb1283133564cb37894
Core/Smilies: The possibilty to resize the smilies has been removed
Bugfix: Added some more simplify_time()
Bugfix: Added AT to the location based date format list
Bugfix: Fixed a wrong link in the mod area
Bugfix: Fixed a display error when using [code]-BBCode