Enable sequentionel writing of device data: DeviceData was always written to the start of the the DD ringbuffer causing everytime a sector erase delay (~200ms). To avoid this the ring buffer functionality has been activated. To be backward compatible the latest DD set will be written to DD ring buffer start at shutdown time. In case of a reset the firmware scans for the latest DD block and restores its content giving the same data consistency intervall (10 minutes) as the previous implementation without having the 200ms penality for sector erases