Merge pull request #622 in ZP/z-push from...

Merge pull request #622 in ZP/z-push from bugfix/ZP-1320-caldav-x-microsoft-cdo-alldayevent to develop

* commit 'd5409db2':
  ZP-1320 Caldav X-MICROSOFT-CDO-ALLDAYEVENT support. Released under the Affero GNU General Public License (AGPL) version 3.

src/backend/caldav/caldav.php

@@ -628,6 +628,12 @@ class BackendCalDAV extends BackendDiff {
                     }
                     break;
 
+                case "X-MICROSOFT-CDO-ALLDAYEVENT":
+                    if ($property->Value() == "TRUE") {
+                        $message->alldayevent = "1";
+                    }
+                    break;
+
                 case "DURATION":
                     if (!isset($message->endtime)) {
                         $start = date_create("@" . $message->starttime);
@@ -995,6 +1001,9 @@ class BackendCalDAV extends BackendDiff {
                 $vevent->AddProperty("X-MICROSOFT-CDO-ALLDAYEVENT", "FALSE");
             }
         }
+        else {
+            $vevent->AddProperty("X-MICROSOFT-CDO-ALLDAYEVENT", "TRUE");
+        }
         if (isset($data->recurrence)) {
             $vevent->AddProperty("RRULE", $this->_GenerateRecurrence($data->recurrence));
         }