* src/gram.h, src/gram.c (error_token_number): Remove, use

errtoken->number.
* src/reader.c (reader): Don't specify the user token number (2)
for $undefined, as it uselessly prevents using it.
* src/gram.h (token_number_t): Move to...
* src/symtab.h: here.
(state_t.number): Is a token_number_t.
* src/print.c, src/reader.c: Use undeftoken->number instead of
hard coded 2.
(Even though this 2 is not the same as above: the number of the
undeftoken remains being 2, it is its user token number which
might not be 2).
* src/output.c (prepare_tokens): Rename the `maxtok' muscle with
`user_token_number_max'.
Output `undef_token_number'.
* data/bison.simple, data/bison.c++: Use them.
Be sure to map invalid yylex return values to
`undef_token_number'.  This saves us from gratuitous SEGV.
* tests/conflicts.at (Solved SR Conflicts)
(Unresolved SR Conflicts): Adjust.
* tests/regression.at (Web2c Actions): Adjust.

src/symtab.h

@@ -41,6 +41,8 @@ typedef enum
   nterm_sym		/* non-terminal */
 } symbol_class;
 
+/* Internal token numbers. */
+typedef short token_number_t;
 #define SUNDEF  -1              /* For undefined user number. */
 #define SALIAS	-9991		/* for symbol generated with an alias */
 
@@ -50,7 +52,7 @@ struct symbol_s
   char *tag;
   /* Its type. */
   char *type_name;
-  short number;
+  token_number_t number;
   short prec;
   associativity assoc;
   int user_token_number;