View test cases revised and passing
Update description of fields applicable only to field entities, to restrict their presentation as a field choice
Update description of fields applicable only to list entities, to restrict their presentation as a field choice
Update description of fields applicable only to type entities, to restrict their presentation as a field choice
Update description of fields applicable only to view entities, to restrict their presentation as a field choice
Add 'annal:field_entity_type' field manually to internal list descriptions, to enable field selection choices
Update view and field definitions for more selective field selection display (issue #16)
Fix problem of ignoring blank value in submitted form (issue #30)