Bugfixes and configurable slug handling

[TASK] Make slug handling configurable #768

This change makes it possible to configure the slug handling TCA settings through extension settings slugBehaviour. If your TYPO3 website has multiple sites that use a shared folder for events, you must configure unique slug handling in slugBehaviour.

This option was added to address an update of the latest TYPO3 core versions, where the uniqueInSite handling has been fixed. See: https://forge.typo3.org/issues/91235

[BUGFIX] Add service definition #757
[BUGFIX] Add missing renderType for datepickermode #762
[TASK] Register Cleanup Command using Service Container #761
[TASK] Removed old 'canNotCollapse' TCA setting
[TASK] Improve TCA of exclude setting
[TASK] Replace last occurrence of "E-Mail" with "Email"
[DOC] Removed RealURL documentation section
[DOC] Fixed several typos #764, #765, #766, #767
[DOC] Added documentation for extension settings