[Feature Request] Option to delete Records that were not in the import file

[tkowtsch]

Use case: ICS file with events is imported via scheduler task. New events are automatically added. Changed events that were imported earlier are updated. But deleted events... remain untouched. Same as old events.

Workaround: Use "delete all records on PID before Import". But with that, all events are imported freshly afterwards. No more update of records, but hundreds of autoincrements in the database, tons of inserts, ...

Proposed solution: Add new config parameter "remove records not related to import". If set,

• create a list of all External EventIDs
• Delete records from PID where import_id NOT IN [list of IDs] and import_source=newsimporticsxml_ics

To save memory and processing time, the list should be created only if this flag is set.