fix buggy EAC date_time getter
change linked_agent_archival_record_roles to static enum
Switch linked_agent i18n entries back to the standard YML file.
added extent types for digital objects
backend support for default enum values
Small comment
41506217 - admins can set default enums
removed dynamic enum callbacks for agent_role_archival_record links
maybe don't have reciprocal fk constraints
Merge branch 'origin-pr-351' (pull request #351)