Add a portal_type attribute to Occurrence objects and set it to 'Occurrence', so they can be easily identified without looking up interfaces.
The event_summary's max_occurrences attribute now also includes the starting event.
fix num_more_occurrences
hide @@sharing button for Occurrence objects, try to dissallow "Copy or Move" permission on context for all (which doesnt work like that)
Disable the edit bar on Occurrence objects. They are transient and cannot be edited. Removing previous experiments to reduce options on edit border