Revert "Revert "Revert "Set the tasklist, if available."""

Reverted the incorrect commit.
This reverts commit a068cd8.

nag/lib/Api.php

@@ -1170,15 +1170,14 @@ public function toggleCompletion($task_id, $tasklist_id)
      * - activesync:       Horde_ActiveSync_Message_Task.
      * - raw:              Nag_Task.
      * @param array $options      Any additional options for the exporter.
-     * @param string $tasklist    The tasklist to look in. @since  4.3.0
      *
      * @return string  The requested data.
      */
-    public function export($uid, $contentType, array $options = array(), $tasklist = null)
+    public function export($uid, $contentType, array $options = array())
     {
         $task = $GLOBALS['injector']
             ->getInstance('Nag_Factory_Driver')
-            ->create($tasklist)
+            ->create('')
             ->getByUID($uid);
         if (!Nag::hasPermission($task->tasklist, Horde_Perms::READ)) {
             throw new Horde_Exception_PermissionDenied();