those whose string ref syntax is unknown or can't be guessed i.e.
don't use it for new documents (prefer user settings in that case)

Conflicts:
	sc/qa/unit/subsequent_export-test.cxx

Change-Id: I1355031cdd63e2a5c50064531011be71ae7f7b8f
Reviewed-on: https://gerrit.libreoffice.org/19244Reviewed-by: Eike Rathke <erack@redhat.com>
Tested-by: Eike Rathke <erack@redhat.com>