STYLE: minor config file details

- move unset mpi buffer size from config.csh/settings -> config.csh/mpi

- wmUNSET now also unalias wmREFRESH

Note: unsetenv WM_COMPILER_TYPE in csh variant?

- drop reference to paraview-3 in config files.
  Cannot say anything definite about support for versions
  this old (2012)

etc/config.csh/mpi

@@ -261,7 +261,6 @@ if ( "$FOAM_MPI" != dummy ) then
 endif
 
 
-
 # Set the minimum MPI buffer size (used by all platforms except SGI MPI)
 # ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 if ( ! $?minBufferSize ) set minBufferSize=20000000
@@ -274,4 +273,8 @@ else
     setenv MPI_BUFFER_SIZE $minBufferSize
 endif
 
+# Cleanup environment:
+# ~~~~~~~~~~~~~~~~~~~~
+unset minBufferSize
+
 #------------------------------------------------------------------------------