Add THcRasterRawHit, THcRasterBeam classes. Add raster_test.C script.

  THcRasterRawHit class to helps with the decoding of the raster
     signals via THcHitList class.
  THcRasteredBeam class derives from THaApparatus to handle rastered beam.
  Modify Makefile and HallC_LinkDef.h to compile new classes