fix #2867 synergia madx import with no beam charge
fix #2867 synergia madx import with no beam charge

radiasoft/sirepo,mkeilman/sirepo,radiasoft/sirepo,radiasoft/sirepo,mkeilman/sirepo,radiasoft/sirepo,radiasoft/sirepo,mkeilman/sirepo,mkeilman/sirepo