ENH: unify sampling code for isoSurfaces, support multiple offsets

src/sampling/Make/files

src/sampling/sampledSurface/isoSurface/sampledIsoSurface.C

src/sampling/sampledSurface/isoSurface/sampledIsoSurface.H

...ampling/sampledSurface/isoSurface/sampledIsoSurfaceCell.C

...ampling/sampledSurface/isoSurface/sampledIsoSurfaceCell.H

...ampledSurface/isoSurface/sampledIsoSurfaceCellTemplates.C

...mpling/sampledSurface/isoSurface/sampledIsoSurfacePoint.C

...mpling/sampledSurface/isoSurface/sampledIsoSurfacePoint.H

...ampling/sampledSurface/isoSurface/sampledIsoSurfaceTopo.C

...ampling/sampledSurface/isoSurface/sampledIsoSurfaceTopo.H

...ampledSurface/isoSurface/sampledIsoSurfaceTopoTemplates.C

.../sampledSurface/sampledCuttingPlane/sampledCuttingPlane.C

.../sampledSurface/sampledCuttingPlane/sampledCuttingPlane.H