of menhir --suggest-ocamlfind, so that the Makefile works when
Menhir is compiled as a Windows executable. (Suggested by Jonathan
Protzenko.)

bindings of the form [x = $i] for ocamlyacc. This should work around a
name capture caused by the fact that ocamlyacc internally translates
[$i] to [_i] (and our own variables are often of the form [_i]).

%type declarations for ocamlyacc. (Reported by Kenji Maillard.)

so as to avoid OCaml's warning 41.

by removing redundant (unused) parameters.

a parser produced by menhir --table cannot be linked with an incorrect
version of MenhirLib.

Updated the table back-end to properly initialize the position in the sentinel cell at the bottom of the stack.
This requires changing the function [start] in the incremental API to take a position.
Updated the doc and demos.

In the previous version, the redefinition of $(libdir) was ineffective when we were called from opam, which overrides $(libdir) from outside.