notes about rdf /sqlalchemy & preliminary groupsheet filter by url
rename current models to rdfmodels to make space for new db models & keep things separate
preliminary dbmodels
rename tei groupsheet class to distinguish from db model
initial db models & data load for people, archival collections, & group sheets; partial group sheet list filtering [#54932972  #49295449]
revert to rdf graph not stored in db
partial correction for tei groupsheets with multiple authors/table of contents
update models & load script to improve rdf handling, add places [#54932972]
update views/templates to rely primarily on db records for list/search views
groupsheet list facets: digital edition, author, source [#49295449 #49308259]