Update parsers to work with Bison 2.4.1.

* HACKING: Mention that we require Bison >= 2.4 for developers.
* src/evtgbaparse/evtgbaparse.yy, src/tgbaparse/tgbaparse.yy,
src/ltlparse/ltlparse.yy: The sections "%{ ... %}" should now be
renamed "%code requires { ... }" or "%code { ... }" depending on
whether they should end up in the parser's header file or its cc
file.  Also use %language, %locations, %defines, instead of
command-line arguments.
* src/evtgbaparse/Makefile.am, src/tgbaparse/Makefile.am,
src/ltlparse/Makefile.am: Remove the --locations, --defines
and --languages in the call to bison.  Add -Wall -Werror to
catch more errors.
Thanks to Akim Demaille <akim@lrde.epita.fr> for the help.

src/ltlparse/ltlparse.yy

@@ -1,4 +1,4 @@
-/* Copyright (C) 2003, 2004, 2005, 2006 Laboratoire d'Informatique de
+/* Copyright (C) 2003, 2004, 2005, 2006, 2009 Laboratoire d'Informatique de
 ** Paris 6 (LIP6), département Systèmes Répartis Coopératifs (SRC),
 ** Université Pierre et Marie Curie.
 **
@@ -19,20 +19,24 @@
 ** Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
 ** 02111-1307, USA.
 */
-%{
+%language "C++"
+%locations
+%defines
+%name-prefix "ltlyy"
+%debug
+%error-verbose
+
+%code requires
+{
 #include <string>
 #include "public.hh"
 #include "ltlast/allnodes.hh"
 #include "ltlvisit/destroy.hh"
+}
 
-%}
-
-%name-prefix="ltlyy"
 %parse-param {spot::ltl::parse_error_list &error_list}
 %parse-param {spot::ltl::environment &parse_environment}
 %parse-param {spot::ltl::formula* &result}
-%debug
-%error-verbose
 %union
 {
   int token;
@@ -40,7 +44,7 @@
   spot::ltl::formula* ltl;
 }
 
-%{
+%code {
 /* ltlparse.hh and parsedecl.hh include each other recursively.
    We mut ensure that YYSTYPE is declared (by the above %union)
    before parsedecl.hh uses it. */
@@ -69,7 +73,7 @@ using namespace spot::ltl;
     }						\
   while (0);
 
-%}
+}
 
 
 /* All tokens.  */