(make-mime-parameter): New inline function.

(make-mime-parameter): New inline function.
(mime-parameter-language): Ditto.
(mime-parameter-set-language): Ditto.
(mime-parameter-set-charset): Ditto.
(mime-parameter-charset): Ditto.
(mime-parameter-raw-values): Ditto.
(mime-parameter-append-raw-value): Ditto.
(mime-parameters): Ditto.
(mime-parameter): Ditto.
(mime-parameter-value): New function.
(mime-content-type-parameters): Use `mime-parameters'.
(mime-content-type-parameter): Use `mime-parameter-value'.
(mime-content-disposition-parameters): Use `mime-parameters'.
(mime-content-disposition-parameter): Use `mime-parameter-value'.