ENH: add top-level Allwclean for paraview plugins

applications/utilities/postProcessing/graphics/PV3Readers/Allwclean

+#!/bin/sh
+cd ${0%/*} || exit 1    # run from this directory
+set -x
+
+wclean libso vtkPV3Readers
+PV3blockMeshReader/Allwclean
+PV3FoamReader/Allwclean
+
+# ----------------------------------------------------------------- end-of-file