This takes readings in the form of ...
<local_1> <remote_1> <remote_2> <local_2>
... with one observation per line, and then replays it using the
netclientclock code.
The output is the statistics structure emitted by the netclientclock,
which can then be analysed and tuned once we get those readings for
potential edge-cases.
It should be possible to find some inputs with "bad" data and convert
this into a unit test for future tweaks to run against.
