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