Implement new MenuItemRenderer made for pages that are not part
of the regular site navigation and should trigger a complete site reload
instead of handling it via XHR.
Add the option to define custom renderers for menu items and implement renderers to
display all unhandled services and host in a badge in the navigation.
resolves#7114
* One less namespace, better naming
* hasItem() added
* throws Exception when trying to access invalid Items
* Automagically creates missing parents when adding named childs
Matthias Jentsch
Thomas Gelf
Eric Lippmann