bug#19274: tar-mode.el: allow for adding new archive members

[Eli Zaretskii]

> From: Ivan Shmakov <ivan@siamics.net>
> Date: Sat, 06 Dec 2014 19:17:16 +0000
> 
> --- a/etc/NEWS        2014-11-27 11:36:08 +0000
> +++ b/etc/NEWS        2014-12-06 19:03:35 +0000
> @@ -340,6 +340,9 @@
>  `tildify-ignored-environments-alist' variables (as well as a few
>  helper functions) obsolete.
>  
> +** tar-mode: new `tar-new-entry' command, allowing for new members to
> +be added to the archive.

How about adding the necessary bits to the Emacs manual?

> +(defun tar-header-serialize (header &optional update-checksum)
> +  "Return the serialization of a Tar HEADER as a string.
> +This function calls `tar-header-block-check-checksum' to ensure the
> +checksum is correct.
> +
> +When UPDATE-CHECKSUM is non-nil, update HEADER with the newly-computed

Not "when", "if".  "When" has an implicit timing reference, which is
not what you mean here.

Thanks.