AtlasHepMC: Improve barcode handling for hepmc3.
Add an attribute to GenEvent containing maps from barcode to GenParticle and GenVertex pointers.
Should dramatically improve the performance issue discussed in ATLASRECTS-7054.
Add an attribute to GenEvent containing maps from barcode to GenParticle and GenVertex pointers.
Should dramatically improve the performance issue discussed in ATLASRECTS-7054.