Propagate more token_number_t.

Propagate more token_number_t.
* src/gram.h (token_number_as_item_number)
(item_number_as_token_number): New.
* src/output.c (GENERATE_OUTPUT_TABLE): New.
Use it to create output_item_number_table and
output_token_number_table.
* src/LR0.c, src/derives.c, src/gram.c, src/gram.h, src/lalr.c,
* src/lex.c, src/nullable.c, src/output.c, src/print.c,
* src/print_graph.c, src/reader.c, src/reduce.c, src/state.h,
* src/symtab.c, src/symtab.h: Use token_number_t instead of shorts.