ENH: CleanFunctions refinements

- include constant/faMesh cleanup (cleanFaMesh) as part of standard
  cleanCase

- simplify cleanPolyMesh function to now just warn about old
  constant/polyMesh/blockMeshDict but not try to remove anything

- cleanup cellDist.vtu (decomposePar -dry-run) as well

ENH: foamRunTutorials - fallback to Allrun-parallel, Allrun-serial

TUT: call m4 with file argument instead of redirected stdin

TUT: adjust suffixes on decomposeParDict variants

tutorials/mesh/snappyHexMesh/sphere_gapClosure/Allclean

@@ -1,8 +1,10 @@
 #!/bin/sh
-cd ${0%/*} || exit 1                        # Run from this directory
-. $WM_PROJECT_DIR/bin/tools/CleanFunctions  # Tutorial clean functions
+cd "${0%/*}" || exit                                # Run from this directory
+. ${WM_PROJECT_DIR:?}/bin/tools/CleanFunctions      # Tutorial clean functions
+#------------------------------------------------------------------------------
 
 cleanCase
-rm *.obj
+
+rm -f *.obj
 
 #------------------------------------------------------------------------------

tutorials/mesh/snappyHexMesh/sphere_gapClosure/Allrun

@@ -1,6 +1,7 @@
 #!/bin/sh
-cd ${0%/*} || exit 1                        # Run from this directory
-. $WM_PROJECT_DIR/bin/tools/RunFunctions    # Tutorial run functions
+cd "${0%/*}" || exit                                # Run from this directory
+. ${WM_PROJECT_DIR:?}/bin/tools/RunFunctions        # Tutorial run functions
+#------------------------------------------------------------------------------
 
 runApplication blockMesh