Add raw time without reference time subtraction to THcDCHit

Add rawnorefcorrtime to THcDCHit which is the TDC raw without
the reference time subtraction.

Add variable rawnorefcorrtdc in THcDriftChamberPlane::DefineVariables

Modify THcDriftChamberPlane::ProcessHits to call GetRawTdcHit().GetTimeRaw
  and call THcDCHit with new extra argument for raw time without reference time
  subtraction.