BUG: snappyHexMesh: fixes #1836.
When truncating layers in one go (nBufferCellsNoExtrude -1) it should set the nCells per face to be the min of the number of points per edge.
When truncating layers in one go (nBufferCellsNoExtrude -1) it should set the nCells per face to be the min of the number of points per edge.