Use lib/hash for the symbol table.

Use lib/hash for the symbol table.
* src/gram.c (ntokens): Initialize to 1, to reserve a slot for
EOF.
* src/lex.c (lex): Set the `number' member of new terminals.
* src/reader.c (bucket_check_defined, bucket_make_alias)
(bucket_check_alias_consistence, bucket_translation): New.
(reader, grammar_free, readgram, token_translations_init)
(packsymbols): Adjust.
(reader): Number the predefined tokens.
* src/reduce.c (inaccessable_symbols): Just use hard coded numbers
for predefined tokens.
* src/symtab.h (bucket): Remove all the hash table related
members.
* src/symtab.c (symtab): Replace by...
(bucket_table): this.
(bucket_new, bucket_free, hash_compare_bucket, hash_bucket)
(buckets_new, buckets_do): New.