Navigation enhancements

[Jotschi]

Fulfill the following requirements:

• Breadcrumbs-Navs must be rendered as easily as possible
• Add a way to specify the activepath - this would make implementations easier
• Add a way to handle a navhidden attribute - this would allow certain nodes / subtrees to be hidden within the nav
• It should be possible to configure the amount of data which would be returned for a navigation request. Otherwise unwanted data would be returned. Check whether GraphQL could be used for this.
• We need a way to filter the navigation elements by types.

[aschauerhuber]

we might also need some kind of sort order within items of a specific navigation level