Shower counter code change that improve agreement with ENGINE.
Added/modified comments to the HMS calorimeter header files
Implemented the clustering debug flag (Mark).
Trace focal plane coordinates to target using COSY reconstruction coefficients.
  Name of coefficient file in hcana.param
  Some basic hms setting parameters added to test.database for run 50017
  Traceback code in THcHalCSpectrometer
Added track extension to the shower counter
Merge branch 'shower3' into develop
Replicate ENGINE tracking better.
1.  nplusminus was not initialized corectly so small angle approximation
was never used.
2.  Change MAXTRACKS from 50 to 10 to match ENGINE.