Shower gtrk

Add small changes in the HMS calorimeter part aimed at making energy of the golden track in hcana more consistent with energy of the best track in Engine. Remove obsolete test code.

   Remove obsolete test code in THcShower class.
   Changes in THcShower and THcShoweCluster classes, in parts of cluster to track association.
   Add a version of THcShowerClass with float precision calculation of the X coordinate of hit clusters in clX()  method.
   Add examples/gtrk_e directory holding scripts for comparison of energies from golden tack in hcana and the best track in Engine.