Implement PID replacement in FixHEPMC
Implement PID replacement in FixHEPMC.
The motivation is https://its.cern.ch/jira/browse/AGENE-2271 and some other issues. If there are PIDS that for some reasons are misused by MCEGs, the way to go might be to replace them after the generation and keep the Simulation code from different workarounds.