Preparatory changes for the HepMC3 migration for packages in AthSimulation

This merge request mainly makes the following replacements for classes which are part of the AthSimulation project:

HepMC::GenParticle* --> HepMC::GenParticlePtr
const HepMC::GenParticle* --> HepMC::ConstGenParticlePtr
HepMC::GenVertex* --> HepMC::GenVertexPtr
const HepMC::GenVertex* --> HepMC::ConstGenVertexPtr

Plus a few other syntax replacements to use helper functions defined in AtlasHepMC/GenParticle.h and AtlasHepMC/GenVertex.h. The purpose is to prepare for the migration from HepMC2 to HepMC3. Further syntax changes will be required.

Simulation/TruthJiveXML/src/TruthTrackRetriever.cxx

@@ -108,7 +108,7 @@ namespace JiveXML {
         phi.push_back(DataType( (thePhi<0) ? thePhi+=2*M_PI : thePhi ));
         eta.push_back(DataType( particle->momentum().pseudoRapidity() ));
         code.push_back(DataType( particle->pdg_id() ));
-        id.push_back(DataType( particle->barcode() ));
+        id.push_back(DataType( HepMC::barcode(*particle) ));
 
         // Get the vertex information
         auto vertex =  particle->production_vertex();