Create LogEntryType definitions for all missing action_types (order changes, check-in events, settings changes of PaymentProviders and TicketOutputs).
Check whether the stored content_object is of the expected model type, preventing incorrect links.
Refactoring:
- Move the base LogEntryType definitions for our models to their own file
- Move HTML escaping into make_link to make it less likely to oversee in the LogEntryType definitions
- Log pretix.event.order.deleted with the deleted Order model as content_object, matching the other *.deleted action_types