Sample usage:

       ./fzp < examples/aust.fzn | ./fz-paccs load name type code halt

Notes:

- AST nodes for fzn parser

TYPE : VALUE

- acceptable types:

- driver process fz-BACK (BACK is back-end specific):

  reads stdin (as produced by bison-generated parser), which results
  in a Prolog term which is the AST.  It then does semantic analysis
  (name & type).

  AST is translated to an IR or actual C code for PaCCS.