-----
* Add :func:`arlib.open` as a shortcut of :class:`Archive` constructor
(:issue:`1`, :pr:`2`).
* Add :func:`is_archive` to determine if a file could be opened
as a valid archive (:issue:`3`, :pr:`4`).
* Add :func:`assert_is_archive` (:pr:`5`).
* Reimplement auto_engine mechanism using *decoutils* package
* Add functionality to check whether a member is a directory or
regular file (:pr:`9`).
* Add functionality to extract members (:pr:`10`).