rather quick & dirty option for language neutral event listing
EN translation for the listing view name
let event be folderish, so that can we can add Images and Files as attachments
quick n dirty custom event type vocabulary
Merge remote-tracking branch 'upstream/master' into ical-sync

Conflicts:
	plone/app/event/browser/event_listing.py
ical importer: Fix default value for imported attendees and categories

Return an empty tuple instead of None so that the edit form can be
rendered.
Add event_uid field, with index, to be used for ical sync