After slicing, set endLayerIndex to target layer + 1
After slicing, set endLayerIndex to target layer + 1

- Issue MatterHackers/MCCentral#3577
After slicing we switch to render n - 1 but show were on n

unlimitedbacon/MatterControl,larsbrubaker/MatterControl,jlewin/MatterControl,larsbrubaker/MatterControl,unlimitedbacon/MatterControl,mmoening/MatterControl,larsbrubaker/MatterControl,jlewin/MatterControl,unlimitedbacon/MatterControl,mmoening/MatterControl,jlewin/MatterControl,jlewin/MatterControl,larsbrubaker/MatterControl,mmoening/MatterControl,unlimitedbacon/MatterControl