[TASK] Introduced FAL fields

The TCA fields for images and files of an event are now using the new
FAL API of TYPO3.
[FEATURE] Enhanced event details rendering

The rendering of the event details (description, images, files, location,
organizer) has been moved to a new EventDetails partial.

The rendering of the description, images and files is now handled by
the default content rendering TypoScript for textpic or uploads content
elements.

For this to work the image rendering needs to be done by FAL (introduced
by https://review.typo3.org/25511/, not yet merged).
[TASK] Updated TCA configuration

For general labels from the lang system Extension the XLIFF files are
now used instead of the old XML / PHP ones.

Addionally some system fields have been updated. They now have the same
configuration as the equivalent fields of the tt_content table.
[TASK] Introduced inline PHPDoc