(char-valid-p): Make it an alias of characterp.

(char-valid-p): Make it an alias of characterp.
(define-charset): Fully re-designed.
(charset-quoted-standard-p): Deleted.
(charsetp): Moved to charset.c.
(charset-info, charset-id, charset-bytes, charset-width,
charset-directioin, charset-iso-graphic-plane,
charset-reverse-charset): Deleted.
(charset-dimension, charset-chars, charset-iso-final-char,
charset-description, charset-short-name, charset-long-name): Call
charset-plist instead of charset-info.
(charset-plist, set-charset-plist): Moved to charset.c.
(get-charset-property, put-charset-property): Moved from
mule-cmds.el.  Call charset-plist and set-charset-plist.
(make-char): Deleted.
(generic-char-p): Make it always return nil.
(decode-char, encode-char): Moved to charset.c.
(coding-spec-XXX-idx): Variables deleted.
(coding-system-iso-2022-flags): New variable.
(define-coding-system): New function.
(transform-make-coding-system-args, make-coding-system): Deleted.
(set-coding-priority): Make it obsolete.
(after-insert-file-set-buffer-file-coding-system): Adjusted for
the new coding system structure.
(find-new-buffer-file-coding-system): Likewise.