STYLE: rationalize tutorial CleanFunctions (related to issue #279)

- include cleanup of other postProcessing directories:
  * Ensight, EnSight, ensightWrite

- don't need to remove files that cleanSnappyFiles already removed:
  * 0/cellLevel 0/pointLevel

- bundle removal of constant/ items together:
  * constant/cellDecomposition constant/polyMesh constant/tetDualMesh