- change name of environment variable from $WM_OS -> $WM_OSTYPE
  as a better description

- Problem: changing between OpenFOAM versions with different
  WM_PROJECT_INST_DIR paths would leave the old paths in the env vars.

- TODO: etc/cshrc is rougned out, but needs work on the corresponding
  if-statement

  - avoid mkdir except for a few directories
  - grouped settings and added comments
  - minor bugfix: $FOAM_INST_DIR/linux64/bin was in path (pre OpenFOAM-1.5)
  - local (non-exported) variables in lowercase

  * prefix internal functions with _foam to prevent collisions
  * cleanup functions after use
  * centralized FOAM_VERBOSE info to etc/{bashrc,cshrc}

  * prefix internal functions with _foam to prevent collisions
  * cleanup functions after use
  * centralized FOAM_VERBOSE info to etc/{bashrc,cshrc}

Changed WM_THIRD_PARTY to WM_THIRD_PARTY_DIR and added to all 'options' files that use third-party software.

set externally