code copied from DasTimeRangeSelector for use with Autoplot. DasTimeRangeSelector wasn't very beany...
creates an instance of the editor, with an arbitrary range (today) loaded.
create an editor with the initial range.
create an editor with the initial range.
Registers TimeRangeSelectionListener to receive events.
adds a droplist of recently entered times. This should be a spacecraft string, or null.
get the GUI panel. All this was because it was firing off events on construction, and I was copying DatumEditor.
Removes TimeRangeSelectionListener from the list of listeners.