* output a PGF grammar in prolog readable syntax
* variables in abstract syntax (hypotheses and lambda-abstractions)
are translated to unique logical variables
* PGF terms in concrete syntax are translated to more prolog-like terms
The old code was brittle, and only converted strings in the lins and opers, not in printnames and parsers. The old code also double encoded some grammars when using gfc to combine PGF files.
