[schema] drop CWSourceSchemaConfig[cw_for_source,cw_schema] unique constraint (closes #1946277)
as they are not necessarily unique, eg when one want a configuration for both
subject and object
# copyright %(year)s %(author)s, all rights reserved.# contact %(author-web-site)s -- mailto:%(author-email)s#%(long-license)s"""%(distname)s entity's classes"""