refactor: commandSocket: object_to_slice ==> mehgroup (CURA-465)
refactor: commandSocket: object_to_slice ==> mehgroup (CURA-465)

ROBO3D/CuraEngine,pratikshashroff/pcura,alephobjects/CuraEngine,totalretribution/CuraEngine,ROBO3D/CuraEngine,ROBO3D/CuraEngine,alephobjects/CuraEngine,Ultimaker/CuraEngine,totalretribution/CuraEngine,pratikshashroff/pcura,alephobjects/CuraEngine,Ultimaker/CuraEngine,totalretribution/CuraEngine,pratikshashroff/pcura