Athena preparation for HepMC3
In this MR: Athena preparation for HepMC3 Mostly simple replacements. Of ofld HepMC2 functions with AtlasHepMC functions that can handle HepMC2 and HepMC3.
In this MR: Athena preparation for HepMC3 Mostly simple replacements. Of ofld HepMC2 functions with AtlasHepMC functions that can handle HepMC2 and HepMC3.