build_trees

  ========================================================================
  USAGE : 
  build_trees myfile.sdf[.[Z|gz]]  [myoutput_file]

  myfile.sdf[.[Z|gz]] is the input data from the ISIS base or the supplied
              sd file. It requires the extension .sdf currently. It may be 
              zipped .Z or compressed .gz


  EXAMPLE:
   ./build_trees /net/sundog/export/home/johnb/ChemStar/chemstar.sdf.gz

  reads input from the compressed sd file 
  /net/sundog/export/home/johnb/ChemStar/chemstar.sdf.gz 
  Output is to /net/sundog/export/home/johnb/ChemStar/chemstar.tdt


  ========================================================================