Time stamps generated by residual.calculate method are inconsistent with residual spreadsheet

The boolean option adjust_reference is used correctly to adjust calculated HDZ absolute values in geomagio.residual.calculate() so that they correspond to the WEST_DOWN measurement time in a given absolute set. However, the time stamps were never changed from their default values.

• force all time stamps to correspond to the WEST_DOWN measurement time if adjust_reference is True; if adjust_reference is False, H and Z absolute times should continue to be associated with the start/end times from inclination measurements, and D absolute times should continue to be associated with the start/end times from declination measurements.