More refactoring of really horrible Solr code.

 - Added test for facet filters and queries
 - Changed from explicit OR queries to implicit ones which rely
   on the default operator, since this cleans up the syntax a lot
Get item count from ngroups rather than matches (fixes #405)
Revert "Add some experimental dir attributes to prompt the browser to detect text direction"

This wasn't ready to go out yet to master.
Merge branch 'master' into virtual_collection_rework