Support loading id, gid and root_gid for attributes in remove relationship edits
Support saving id, gid and root_gid for attributes in remove relationship edits
Link relationship edits to instrument edit histories
Merge remote-tracking branch 'nikki-bitbucket/store-ids-remove-relationship'

* nikki-bitbucket/store-ids-remove-relationship:
  Link relationship edits to instrument edit histories
  Support saving id, gid and root_gid for attributes in remove relationship edits
  Support loading id, gid and root_gid for attributes in remove relationship edits