handle spot logs correctly

[n1ywb]

spotter logs would be interesting to map but they have the meaning of the 'operator' and 'call' fields reversed which confuses Log.georeference()

it should be easy enough to fix by looking for the operator field on every qso record instead of just the first one and drop a new point if the call hasn't been mapped already; that would also help with multi-station log handling (if any such thing is ever tried).