[Client] Updated namespace decleration of GUI xml files

The current version of the Nifty-GUI uses a new namespace file. This is not applied.
[Client] Fix music settings

The music settings are now properly applied to the playback devices.
[Build] Removed usage of deprecated classes
[Common] Library Update MantisConnect

The mantis connect library got a update from 1.1.1.1 to 1.1.2.0-SVN
[Client] Fixed updating of news entries

Switching the displayed news entry now work a lot better. The text is only shown
once displaying the new text components is done.
Fixing issue 9144
[Client] Updating quest marker elevation properly

The quest marker elevation is now updated in case a character becomes visible.

Fixing issue 9145
[Client] Updating quest marker elevation properly

Also update the quest marker is a character disappears