DNP3 timestamps and Sequence of Events (SOE)

[Adam Crain]

I just committed a change to master that will have significant impact
on applications that use the master.

Previously, the master timestamped measurements with system time if
there was no device time stamp. The source of the time was being lost
in the translation.

The master no longer timestamps measurements with system time. Points
that didn't come from the field with a timestamp (static data and no
time carrying events) will have the time == 0, Unix epoch January 1st
1970. It is the responsibility of the consumer to apply system time to
these measurements.

This implicit approach allows the consumer to decide how to handle non
timestamped data.

-Adam