Log Message:
Update to 2.5.0beta1:

* The vertical 3-paned view mode was added.
* The feature to save SSL peer certificate was added.
* The option 'Treat HTML only message as attachment' was added.
* The bug that caused busy loop when initial connection was
  immediately refused was fixed.
* The bug that the quote description dialog never appeared again
  after closing it with the close button was fixed.
* The new/unread status display on quick search filtered mode was fixed.
* The windres command will not be enabled on non-win32 platforms now.