Start adding to the drift chamber code.   Setup a class structure
      similar to what podd uses for the VDCs.  Raw hit class renamed
      to THcRawDCHit.  Signal hits are how THcDCHit, modeled after
      podd hits.  Add THcDCWire, and classes for time to distance conversion.
      Time to distnace conversion doesn't do anything yet.

      Find some improved DC parameter files so that min and max TDC limits
      are good for the run we are using.

      THcDriftChamberPlane asks ThcDriftChamber for many parameters.

Put map files in MAPS subdir.
Define correct map for run 50017 in test.database.
Add a script to display drift chamber hitmaps.
Fix make_cratemap.pl so that it makes an entry in db_cratemap.dat
  for all Fastbus slots.