ENH: snappyHexMesh: add -dry-run argument. See #972.

...s/utilities/mesh/generation/snappyHexMesh/snappyHexMesh.C

src/OpenFOAM/db/error/error.C

src/OpenFOAM/db/error/error.H

src/dynamicMesh/motionSmoother/motionSmoother.C

src/dynamicMesh/motionSmoother/motionSmoother.H

src/dynamicMesh/motionSmoother/motionSmootherAlgo.C

src/dynamicMesh/motionSmoother/motionSmootherAlgo.H

src/dynamicMesh/motionSmoother/motionSmootherAlgoCheck.C

src/dynamicMesh/motionSmoother/motionSmootherAlgoTemplates.C

src/mesh/snappyHexMesh/Make/files

src/mesh/snappyHexMesh/Make/options

...DisplacementMeshMover/displacementMotionSolverMeshMover.C

...DisplacementMeshMover/displacementMotionSolverMeshMover.H

...rnalDisplacementMeshMover/externalDisplacementMeshMover.C

...rnalDisplacementMeshMover/externalDisplacementMeshMover.H

...xMesh/externalDisplacementMeshMover/medialAxisMeshMover.C

...xMesh/externalDisplacementMeshMover/medialAxisMeshMover.H

src/mesh/snappyHexMesh/meshRefinement/meshRefinement.C

src/mesh/snappyHexMesh/meshRefinement/meshRefinement.H

...sh/snappyHexMesh/meshRefinement/meshRefinementGapRefine.C