plugin=diff is not implemented.
http://tuotehhou.y.ribbon.to/index.php?%E3%83%95%E3%82%A1%E3%83%B3%E3%82%AF%E3%82%B7%E3%83%A7%E3%83%B3%E3%83%9D%E3%82%A4%E3%83%B3%E3%83%88
plugin=diff is not implemented.