Fix an issue with the correction factor locking to 0.95.

Fix an issue with the correction factor locking to 0.95.

Basically what was happening is that if the master card lost
or corrupted a frame, which we didn't set a timestamp on,
causing it to have steady_clock::time_point::min(). This would
in turn cause us to assume a latency of trillions of seconds,
throwing off the filter and essentially making it be 0.95 forever.

The fix is twofold; we always set timestamps, but also make
ourselves robust to the ones that are way off (negative uptime).