Port of fixes from HepMC3 branch into master
Port of fixes from HepMC3 branch into master. In this MR:
- Instead of removing bad particles try to apply some heuristics: check if broken particles can be fixed adding one vertex that would constitute to 1->, 2->1 or 1-> splitting/merging. Essentially this is a workaround for a generator bug.
- Remove the particles with bad pdg ID from the event record.
Edited by Andrii Verbytskyi