fix: concentric infill doesn't oscilate because of alternate extra wall (CURA-2772)
fix: concentric infill doesn't oscilate because of alternate extra wall (CURA-2772)

because the innermost wall was different every layer, the concentric infill was also shifted every layer

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