fix: command line slicing was broken (CURA-833)
fix: command line slicing was broken (CURA-833)

totalretribution/CuraEngine,Ultimaker/CuraEngine,alephobjects/CuraEngine,totalretribution/CuraEngine,ROBO3D/CuraEngine,alephobjects/CuraEngine,alephobjects/CuraEngine,ROBO3D/CuraEngine,totalretribution/CuraEngine,Ultimaker/CuraEngine,ROBO3D/CuraEngine