Rewrite (Get|Stat)Message by using faster/simpler HREF search & improve UID search

Requires !3 (merged)

Fixes MMMMALT-1049

src/backend/caldav/caldav.php

@@ -257,13 +257,12 @@ class BackendCalDAV extends BackendDiff {
         $path = $this->_caldav_path . substr($folderid, 1) . "/";
         $href = $path . $id;
         ZLog::Write(LOGLEVEL_DEBUG, sprintf("BackendCalDAV->GetMessage Querying server for message with href '%s' in folder '%s'", $href, $path));
-        $messages = $this->_caldav->CalendarMultiget( array( $href ), $path );
-        if (!isset($messages[$href]) || $messages[$href] == '') {
+        $message = $this->_caldav->GetEntryByHref($href);
+        if ($message == null || $message['data'] == '') {
             //we don't have any ical information, return false so that the diff backend raises an exception
             return false;
         }
-        $data = $messages[ $href ];
-        unset ($messages, $href);
+        $data = $message['data'];
         if ($folderid[0] == "C") {
             return $this->_ParseVEventToAS($data, $contentparameters);
         }
@@ -279,23 +278,19 @@ class BackendCalDAV extends BackendDiff {
      */
     public function StatMessage($folderid, $id) {
         ZLog::Write(LOGLEVEL_DEBUG, sprintf("BackendCalDAV->StatMessage('%s','%s')", $folderid,  $id));
-        $type = "VEVENT";
-        if ($folderid[0] == "T") {
-            $type = "VTODO";
-        }
         $data = null;
         if (array_key_exists($id, $this->_collection)) {
             $data = $this->_collection[$id];
         }
         else {
             $path = $this->_caldav_path . substr($folderid, 1) . "/";
+            $href = $path . $id;
             ZLog::Write(LOGLEVEL_DEBUG, sprintf("BackendCalDAV->StatMessage Data doesn't exist for this item, querying caldav server for uid '%s' in folder '%s'", substr($id, 0, strlen($id)-4), $path));
-            $e = $this->_caldav->GetEntryByUid(substr($id, 0, strlen($id)-4), $path, $type);
-            if ($e == null && count($e) <= 0) {
+            $data = $this->_caldav->GetEntryByHref($href);
+            if ($data== null) {
                 ZLog::Write(LOGLEVEL_DEBUG, sprintf("BackendCalDAV->StatMessage No item on server with uid '%s' in folder '%s'", substr($id, 0, strlen($id)-4), $path));
                 return;
             }
-            $data = $e[0];
         }
         $message = array();
         $message['id'] = $data['href'];