Log Message:
Update to 2.2.6.

Changes 2.2.6:

    * The 8-bit literal (literal8) in IMAP4 response was supported.
    * The missing timeout handling was added for SMTP.
    * The failure of URI security check when they have leading space
      was fixed.

Changes 2.2.5:

    * The character corruption and crash bug when using Japanese
      half-width kana on sending messages was fixed.
    * The execution failure when using the accessibility module was fixed.
    * The bug that new/unread count becoming negative value was fixed.
    * The bug that bold face was disabled in the folder selection dialog
      with GLib 2.10 and Pango 1.12 was fixed.
    * The incorrect progressbar display when expired messages exist was
      fixed.