fix #1259 wrong x units for spectral detuning report
fix #1259 wrong x units for spectral detuning report

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