Completely reworked navigation and page-managers. This changes is
significant, while it works (and is fully tested). I have yet to update
the list-of-things widgets to fit into the new framework.
Small addition to the abstract template; I dont believe the prev|next links are useless
Merge pull request #161 from romanchyla/new-navigation

New navigation. WARNING: things are not working properly inside the application (yet!) - it is mostly about missing configuration.