make group autocompletion work again

fixes #5

admin/getgroups.php

@@ -56,12 +56,13 @@ function getGroups($part) {
   $last_string = trim(array_pop($array));
   $retval = array();
   if ($last_string != '') {
+    $prefix = count($array) ? implode(",", $array) . ", ": '';
     $groups = file($GLOBALS['davconfig']['group.file']);
     foreach ($groups as $line) {
       list($group, $users) = explode(":", $line);
       $group = trim($group);
       if (stripos($group, $last_string) === 0) {
-        array_push($retval, $group);
+        $retval[$prefix . $group] = $group;
       }
     }
   }