User action that sets G4 looper threshold values

This user action can configure the looper threshold values in Geant4: http://www-geant4.kek.jp/lxr/source/processes/transportation/src/G4Transportation.cc#L878

The preInclude will set them both to 0 for debugging purposes. By default, Geant4 would only print Exceptions for particles above 100 MeV.

The user action also calls a Geant4 printout method, e.g.:

G4Transportation:  Current values for thresholds related to  the killing of looping tracks:
Warning Energy   = 0 MeV   ( below this tracks are killed without warning )
Important Energy = 0  ( above this tracks are given multiple chances )
Extra Trials     = 10 'important' tracks, i.e. those above 'important' energy