* check for existing processor*/ before creating mesh
 * require processor dirs with -fields option
 * new -force option to remove existing processor*/
 * added usage for Doxygen

remaining bug:
 * -cellDist does not write cellDecomposition labelList when
   region0/ does not already exist

sliced fields.

  * output full file path
  * some preliminary file edits to restore 80-col max.