Moved useful EvtGenExtras models to EvtGen (LHCBGAUSS-1478)
Moved useful models in EvtGenExtras ("LHCb-only") to EvtGen itself so that we can include them in the synced HepForge EvtGen release to benefit the wider community.
See LHCBGAUSS-1478.
These changes will also be suitable for Sim10 releases.
Edited by Gloria Corti