Stacks, clog

[Hans Aberg]

Some question:

- The Bison generated parser currently uses up to three stacks. I think of
merging them into a single one. Is there any advantage of having them apart?

- Under C++, one has three standard output streams, cout, cerr and clog,
where clog differs from cerr in that it can be buffered (thus may be
faster). (If not redirected they all point at the same output.) I think of
putting error messages on cerr and debug messages on clog. What do ya think
about that?

  Hans Aberg