Maintenance and bugfix release
[FEATURE] Add settings to variables in Modify*ViewVariablesEvents #1071
[FEATURE] Added ModifyPaymentRedirectResponseEvent PSR-14 event #1082
[BUGFIX] Check for proper array #1074 - thanks @georgringer
[BUGFIX] Show all levels in flexform category tree #1092 - thanks @Mabahe
[TASK] Use different method to check registrationfields #1068 - thanks @georgringer
[TASK] Add translation for word week in Calendar.html template #1078