: new( dirname ) -> TMail::Maildir
    dirname: String

     TMail::Maildir ֥Ȥޤ
    dirname  maildir ᡼ܥåȤƻȤǥ쥯ȥ̾Ǥ
    ǥ쥯ȥϤǤ˺ߤǤʤФޤ

