Bug fixes and refactoring concerning query facets.

 - combining query facets in a tag/exclude union now works
 - multiple query facets are correctly handled as a union by being
   applied within the same fq parameter (instead of multiple)
 - simplification to the filter application code
Use a choice facet for LOD estimation

 - this allows, e.g. using both medium and high LOD
Consolidate rendering of annotations in different contexts.

An enum is now used as a path parameter to specify which one of
field, block, or list annotation rendering is required.