Add a real time timestamp to each message

[spbnick]

As tlog-rec always caches the recorded data for at least one second, the timestamp the log server adds lags behind and doesn't represent the exact time the input was done, which might make correlating with other log messages more difficult.

Implement adding a real time timestamp to each message signifying the real and absolute time the first timing entry has arrived.

[spbnick]

The problem here is that then tlog messages would need to be handled differently from all others in the log, because the accurate timing data would be inside the message. Perhaps we can live with the imprecision.

[spbnick]

If we're going to add this, then the field name should match the one aushape uses.