make groupsheet time period encoded in TEI available via RDF as dc:coverage to support displaying groupsheets by time period [#50478823]
add coverag attribute to groupsheet rdf model, for displaying groupsheets by time period [#50478823]
clean up rdf namespace references
qub title correction to improve de-duping
generate local profile uris before smushing groupsheets so author uris will be available
infer date coverage (second/first period of belfast group) for groupsheets based on date, collection (first pass) [#50478823]
add logic to facet groupsheets on time period [#50478823]