ISF_Fatras HitCreators use position-based HepMcParticleLinks
Update the ISF_Fatras HitCreators to use eventIndex=0 and HEPMC::IS_POSITION, rather than eventIndex=0 and HEPMC::IS_EVENTNUM.
Update the ISF_Fatras HitCreators to use eventIndex=0 and HEPMC::IS_POSITION, rather than eventIndex=0 and HEPMC::IS_EVENTNUM.