ENH: snappyHexMesh: buffer layers on faceZones.

...esh/snappyHexMesh/snappyHexMeshDriver/snappyLayerDriver.C

...esh/snappyHexMesh/snappyHexMeshDriver/snappyLayerDriver.H

...HexMesh/snappyHexMeshDriver/snappyLayerDriverSinglePass.C

...mesh/snappyHexMesh/snappyHexMeshDriver/snappySnapDriver.C

...mesh/snappyHexMesh/snappyHexMeshDriver/snappySnapDriver.H

...exMesh/snappyHexMeshDriver/snappySnapDriverBufferLayers.C

tutorials/mesh/snappyHexMesh/sphere_multiRegion/Allclean

tutorials/mesh/snappyHexMesh/sphere_multiRegion/Allrun

tutorials/mesh/snappyHexMesh/sphere_multiRegion/README.txt

...snappyHexMesh/sphere_multiRegion/constant/dynamicMeshDict

...pyHexMesh/sphere_multiRegion/constant/transportProperties

...esh/snappyHexMesh/sphere_multiRegion/system/blockMeshDict

.../mesh/snappyHexMesh/sphere_multiRegion/system/controlDict

.../snappyHexMesh/sphere_multiRegion/system/decomposeParDict

...ls/mesh/snappyHexMesh/sphere_multiRegion/system/fvSchemes

...s/mesh/snappyHexMesh/sphere_multiRegion/system/fvSolution

...h/snappyHexMesh/sphere_multiRegion/system/meshQualityDict

...snappyHexMesh/sphere_multiRegion/system/snappyHexMeshDict