THcDCTrack class changes.
  The THcDCTrack class now saves a list of space point pointers instead
    of space point indices.
  The AddSpacePoint method now also copies all the hit information into
    the track object so that THcDC doesn't need to explicitely copy all
    the hits.
Copy the hit distance and LR information into THcDCTrack.
Remove unused code that adds hits to track.
Use the hdc_fix_lr and hdc_fix_propcorr choices in track fitting.