Fixed logging of TCP communication.

Reading from TCP sockets was being reported with the time at which the
read starts. This is _very_ wrong as read has often to block for
considerable time waiting for data. Moreover, negative calibration could
even cause reporting data received with a time before it was sent.
Disabling periodical logging of simulated CPU usage.

It was not working right with the parallel simulation kernel,
making time advance too much. An alternative needs to be
found.