adjusted and improved buildParaView script

  - usage, explicit -fast option for rebuilding new -mpi, -python, -mesa
    options for specifying alternative modules to include without editing
    the file
  - the build options can also be grabbed from the script name itself.
    eg, the soft-link buildParaView3.3-cvs-python specifies that the python
    module should be included
  - misc. cleanup in tools/buildParaViewFunctions: give the user some
    feedback about the python version, set all variables at the bottom
    of the file rather between initialise and build.
  - be more careful when changing the hard-links to avoid the find
    '-execdir' option (fails when the user has '.' in the path), and
    do separate find/loop/grep/sed on the files to avoid touching too many
    files and ruining a later rebuild stage.

Notes:
  - the cmake uses -DCMAKE_INSTALL_PREFIX=$PARAVIEW_APP_DIR, but this
    variable isn't defined anywhere.