Adjust window of events to calendar sync

- In order to avoid very large request sets to the calendar provider, the window here is reduced to 3 months in the past until Dec 31 of the next year.

model/facade/action/SyncCalendarAction.php

@@ -57,9 +57,9 @@ protected function doExecute()
 
         $client->setCalendar($arrayOfCalendars[ConfigurationParametersManager::getParameter('CALENDAR_ID')]);
 
-        $lastYear = date("Y") - 1;
         $nextYear = date("Y") + 1;
-        $start = gmdate("Ymd\THis\Z", strtotime($lastYear . "-01-01"));
+
+        $start = gmdate("Ymd\THis\Z", date(strtotime("-3 months")));
         $end = gmdate("Ymd\THis\Z", strtotime($nextYear . "-12-31"));
         $currentEvents = $client->getEvents($start, $end);
         foreach ($currentEvents as $event) {
@@ -69,8 +69,7 @@ protected function doExecute()
         }
 
         foreach ($this->datesRanges as $range) {
-            if (!is_array($range) || !isset($range['start'])) continue;
-
+            if (!is_array($range) || !isset($range['start']) || $range['start'] < $start) continue;
             $start = str_replace("-", "", $range['start']);
             $end = str_replace("-", "", $range['end']);
             $userEmail = $this->user->getLogin() . "@" . $companyDomain;