fixed evt ID, fixed zero eng photons

MC downstream respects only HEP EVT IDs 1 (pass to Geant), and 2
(ignore). Zero energy photons caused problems downstream, too.
added hepmcutil to convert hepmc file into a mdst file

it's a basf module to replace other event generators
added general purpose MC launch script

event generator, decay generator, hepmc converter, mdst converter,
geant4