Log Message:
Update to 2.2.0.

* 2.2.0 (stable)

    * The move and copy of messages to queue folders and virtual folders are
      prohibited.
    * The included sylpheed.spec was modified.

* 2.2.0rc (development)

    * The 'minimize to tray icon' feature was modified.
    * The command line options help dialog is not duplicated anymore.
    * The problem that the UI was still insensitive after the execution of
      external editor failed was fixed.
    * The nonstandard Japanese encoding 'x-sjis' was supported.
    * Win32: The locale encoding problem on some languages was fixed.