Several new features and improvements

[FEATURE] Added signal in EventRepository for findDemanded() #565
[FEATURE] Add singleEvent flexform setting for detail and registration page #568
[FEATURE] Add cache tags in list and detail action with flush on save #571
[FEATURE] Add description column #573
[BUGFIX] Unable to edit dates in localized events for TYPO3 7.6 #583
[TASK] Show category menu setting in flexform for search action #566
[TASK] Use default upload temp folder for CSV export
[TASK] Add "speaker" to searchDemand #567
[TASK] Replace LLL:EXT:cms label in speaker TCA #570
[TASK] Replace renderMode with renderType in Flexform_plugin.xml #569
[TASK] Disable cHash check for payment plugin #564
[TASK] Assign registraton object to view in confirmRegistrationAction #577
[TASK] Enable full text search for feuser field in registration #554
[TASK] Allow cancellation of registration when no deadline is set #585