refactor: typo iddle ==> middle (CURA-579)
refactor: typo iddle ==> middle (CURA-579)

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