made rafts' combing not depend on nozzle_size (CURA-1097)
made rafts' combing not depend on nozzle_size (CURA-1097)

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