4 new features and some bugfixes

[FEATURE] Add support to show event calendar by weeks #980
[FEATURE] Add url for organisator #979 - thanks @format-gmbh
[FEATURE] Add substractChars argument to ICalendarDescriptionViewHelper #992
[FEATURE] Introduce metadata fields #987

[TASK] Remove superfluous tab "payment" in TCA #986
[TASK] Use f:format.nl2br() for custom log details #985 - thanks @christophlehmann
[TASK] Add CustomNotification to ModifyCustomNotificationLogEvent #984 - thanks @christophlehmann

[BUGFIX] Respect type of mainRegistration property on waitlist moveup #976
[BUGFIX] handle multibyte characters in iCal description #990 - thanks @rr-it
[BUGFIX] fold long text for SUMMARY and LOCATION in iCal #991 - thanks @rr-it