EPOS.py mod.: light particle event types not using pythia, but EPOS
Port merging of branch 'LHCBGAUSS-1320.EposforLFevttypes' into 'Sim09'
See merge request !259 (merged), also correspond to !261 (merged) merging to master
(cherry picked from commit 9616f3af)
f44a9d35 EPOS.py mod.: light particle event types not using pythia, but EPOS