(initialize-instance): New method.

(initialize-instance): New method.
(mime-entity-name): Fixed.
(mmexternal-require-buffer): New function.
(mime-insert-entity): New implementation.
(mime-write-entity): Likewise.
(mime-entity-body): New method.
(mime-insert-entity-body): New method.
(mime-write-entity-body): New implementation.
(mime-entity-content): Likewise.
(mime-insert-entity-content): Likewise.
(mime-write-entity-content): Likewise.
(mime-entity-fetch-field): Likewise.
(mime-insert-header): Likewise.