/mandos/release

Use the new Client.LastCheckerStatus property.
* mandos-monitor (MandosClientWidget.last_checker_failed): Removed.
  (MandosClientWidget.property_changed): Check for LastCheckerStatus
                                         and enable timer if failure
                                         is indicated.
  (MandosClientWidget.update): Use LastCheckerStatus property instead
                               of last_checker_failed.