(make-mime-entity-internal): Change interface and data format for NOV

(make-mime-entity-internal): Change interface and data format for NOV
data.
(mime-entity-set-location-internal): New function.
(mime-entity-decoded-subject-internal): New function.
(mime-entity-set-decoded-subject-internal): New function.
(mime-entity-decoded-from-internal): New function.
(mime-entity-set-decoded-from-internal): New function.
(mime-entity-date-internal): New function.
(mime-entity-set-date-internal): New function.
(mime-entity-message-id-internal): New function.
(mime-entity-set-message-id-internal): New function.
(mime-entity-references-internal): New function.
(mime-entity-set-references-internal): New function.
(mime-entity-chars-internal): New function.
(mime-entity-set-chars-internal): New function.
(mime-entity-lines-internal): New function.
(mime-entity-set-lines-internal): New function.
(mime-entity-xref-internal): New function.
(mime-entity-set-xref-internal): New function.
(mime-entity-original-header-internal): Modify for new structure.
(mime-entity-set-original-header-internal): Likewise.
(mime-entity-parsed-header-internal): Likewise.
(mime-entity-set-parsed-header-internal): Likewise.
(mime-entity-buffer-internal): Likewise.
(mime-entity-set-buffer-internal): Likewise.
(mime-entity-header-start-internal): Likewise.
(mime-entity-set-header-start-internal): Likewise.
(mime-entity-header-end-internal): Likewise.
(mime-entity-set-header-end-internal): Likewise.
(mime-entity-body-start-internal): Likewise.
(mime-entity-set-body-start-internal): Likewise.
(mime-entity-body-end-internal): Likewise.
(mime-entity-set-body-end-internal): Likewise.