* add support for dynamic interfaces in ifAlias script
* netlink and ip support alias (`ip link set IFACE alias ALIAS`). In an
environment with dynamic interfaces, it is useful to be able retrieve
aliases from ip.
* we cannot assume next iface oid is n + 1 since oids do not necessarily
follow incrementally when some interfaces has been destroyed and
recreated.
* use straight POSIX shell
* I agree to the conditions of the Contributor Agreement contained in
doc/General/Contributing.md.
