Adds 'external_ref' column to OccurrencesInLine
Adds 'external_ref' column to OccurrencesInLine

ic-labs/icekit-events,ic-labs/icekit-events,ic-labs/django-icekit,ic-labs/django-icekit,ic-labs/icekit-events,ic-labs/django-icekit,ic-labs/django-icekit