fix network statistics
Statistics is useful to understand the asapo bottlenecks and check current performance. Receiver statistics estimate time receiver spent in doing networking. Call Receive
in the RequestDispatcher::GetNextRequest
may take quite long if connection to receiver is established, but receiver didn't send data jet. Or sends data with intervals. Therefore I introduced a new category (that will show-up in the influxDB) to distinguish a data-transfer from network listening.