ics_export extensibility

[ale-rt]

The following lines:

plone.app.event/plone/app/event/ical/exporter.py

Lines 54 to 57 in 4e6ec13

	if not (IEvent.providedBy(event) or IOccurrence.providedBy(event)):
	# Must be an event.
	continue
	acc = IEventAccessor(event)

make it hard to extend the the ics_view to include other content types that do not directly provide the IEvent interface.

IMO the code should be changed to digest everything that can be adapted succesfully, i.e:

        acc = IEventAccessor(event, None)
        if not acc: 
            continue
        component = IICalendarEventComponent(event, None)
        if not component:
            continue

[ale-rt]

I hope I can deliver a PR for this, but that will not happen not soonish...