Example14 misses EM processes for muons, hadrons, ions

In

AdePT/examples/Example14/src/FTFP_BERT_HepEm.cc

Lines 37 to 39 in 85d79b8

    
           // EM Physics 
        
           //  RegisterPhysics( new G4EmStandardPhysics(ver)); 
        
           RegisterPhysics(new PhysListHepEm);

we completely disable G4EmStandardPhysics and replace it with PhysListHepEm, which uses G4HepEm but only for electrons, positrons and gammas. This works fine as long as we stay in the closed domain of those particles, but will lead to problems if we simulate a pion shower, for example. What we're missing is (at least) the equivalent of https://github.com/Geant4/geant4/blob/84f33a068c5e0acb278dc4e4acb6a2822c6e7bca/source/physics_lists/constructors/electromagnetic/src/G4EmStandardPhysics.cc#L222-L233

I have added the missing part in https://github.com/WitekPokorski/AdePT/blob/xtraem/examples/Example14/src/PhysListHepEm.cc
I think, it's OK now, but to be tested.
Please let me know if you see any side effects.

	// EM Physics
	// RegisterPhysics( new G4EmStandardPhysics(ver));
	RegisterPhysics(new PhysListHepEm);