Filter out noise from the logging trace

[M4rtinK]

Sometimes the GPS fix is temporarily lost or the reception gets worse for a while (going through a tunnel/waling through a building, deep valley, etc.) there might be a few spurious position fixes that result in a very weird looking trace being drawn.

It would be good to filter those out based on the sudden position change, but of course without throwing out real data if possible. People riding solid propelled rockets or naval fighter jet pilots might want to turn the filtering off as their logging traces might be unrecognizable from GPS noise. :)