Allow time zone adjustment for results files

[Maprunner]

trafficstars

Some results files seem to have the start and finish times in GMT rather than the local time zone.

Conisder adding an option to add/subtract a fixed offset to all start times (RG2 manager doesn't use the finish time). Probably best on the configuration dialog, with a default of 0. Then put up a warning in the manager if you set up an event with any value other than 0.