Add possibility to add birthdays + repeating events to the API

src/models/calendar/events/icalgenerator.service.ts

@@ -53,6 +53,7 @@ const serializeIcalEvent = (icalevent: iCalEvent): string => {
 		returnString += 'DTSTART;TZID=Europe/Berlin:' + icalevent.start;
 		returnString += 'DTEND;TZID=Europe/Berlin:' + icalevent.end;
 	}
+    if(!isNullOrBlank(icalevent.repeatFrequency)) returnString += 'RRULE:FREQ=' + icalevent.repeatFrequency;
 	returnString += 'SUMMARY:' + icalevent.summary;
 	if(!isNullOrBlank(icalevent.description)) returnString += 'DESCRIPTION:' + icalevent.description;
 	if(!isNullOrBlank(icalevent.location)) returnString += 'LOCATION:' + icalevent.location;
@@ -126,6 +127,7 @@ const createIcalEvent = (event: Event): iCalEvent => {
 		organizer: event.createdBy + '\n',
 		start: formatDate(event.startDateTime, event.wholeDay) + '\n',
 		end: formatDate(event.endDateTime, event.wholeDay, true) + '\n',
+        repeatFrequency: event.repeatFrequency ? event.repeatFrequency + '\n' : '',
 		summary: event.name + '\n',
 		description: description,
 		location: location,
@@ -178,6 +180,7 @@ export interface iCalEvent {
 	location: string;
 	url: string;
 	wholeDay: boolean;
+    repeatFrequency: string;
 	footer: string;
 }