* If the user does not define YYSTYPE as a macro, Bison now declares it

* If the user does not define YYSTYPE as a macro, Bison now declares it
  using typedef instead of defining it as a macro.  POSIX requires this.
  For consistency, YYLTYPE is also declared instead of defined.

* %union directives can now have a tag before the `{', e.g., the
  directive `%union foo {...}' now generates the C code
  `typedef union foo { ... } YYSTYPE;'; this is for Yacc compatibility.
  The default union tag is `YYSTYPE', for compatibility with Solaris 9 Yacc.
  For consistency, YYLTYPE's struct tag is now `YYLTYPE' instead of `yyltype'.

* `yystype' and `yyltype' are now obsolescent macros instead of being
  typedefs or tags; they are no longer documented and will be
  withdrawn in a future release.

Fix copyright notice.