LayerBuffer bugfixes
LayerBuffer bugfixes

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