(enum define_charset_arg_index): Delete

(enum define_charset_arg_index): Delete
charset_arg_parents and add charset_arg_subset and
charset_arg_superset,.
(enum charset_attr_index): Delete charset_parents and add
charset_subset and charset_superset.
(enum charset_method): Delete CHARSET_METHOD_INHERIT and add
CHARSET_METHOD_SUBSET and CHARSET_METHOD_SUPERSET.
(CHARSET_ATTR_PARENTS, CHARSET_PARENTS): Macros deleted.
(CHARSET_ATTR_SUBSET, CHARSET_ATTR_SUPERSET, CHARSET_SUBSET,
CHARSET_SUPERSET): New macros.
(charset_work): Extern it.
(ENCODE_CHAR): Use charset_work.
(CHAR_CHARSET_P): Adjusted for the change of encoder format.
(map_charset_chars): Extern it.