Uniform frontend components and mechanics

[tbergmueller]

Note this may best work with a temporary feature freeze

At the moment, the UI-mechanic and design is duplicated to each individual component. This is hard to maintain and not robust. We shall split this out into different components which can be reused by each page.

This includes

• The NavBar (path of current page)
• Page titles
• Wording (example, when I change the name of a menu item I have to change the Sidebar, the and the page itself). Here something like locale makes sense.

[tbergmueller]

Also optimization for mobile is needed. Especially UI should also work from the MetaAnchor mobile app's browser