commit a56eab8259568ea1389e972623e46359e73c0233

    Allow for adding new members to Tar archives.

    * lisp/tar-mode.el: Allow for adding new archive members.
    (tar-new-regular-file-header, tar--pad-to, tar--put-at)
    (tar-header-serialize): New functions.
    (tar-current-position): Split from tar-current-descriptor.
    (tar-current-descriptor): Use it.
    (tar-new-entry): New command.
    (tar-mode-map): Bind it.
    * doc/emacs/files.texi (File Archives): Document "I" for tar-new-entry.
    * etc/NEWS: Mention the new tar-new-entry command.

    Fixes: debbugs:19274