Ftw-events

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- Make EventFolder and EventListingBlock addable on the Plone Site.
[lknoepfel]

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- Change German translation for event listing block. [jone]

- Fix AttributeError in create_event_listing_block. [jone]

- Added action for ics export. [tschanzt]

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- Fixed bug where default value on eventlistingblock was not set. [lknoepfel]

- Added ftw.calendar integration. [lknoepfel]

- Don't list EventPage in the navigation [lkoepfel]

- Initial implementation [jone]