[Babel-users] MAC auth. for Babel in babeld

[Antonin Décimo]

> - make "use both" optional;

I dislike "use both" anyway. I’ve removed it. If you don't specify the
use, then the key is used for signing and verifying. If you specify a
use, then the key is used only for it.

> - rename "add-keyset" to just "keyset";

I disagree, this would break symmetry with "rm-keyset".

> - rename "keyset-add-key" to just "add-key";

Done.

> - allow the interface configuration to say "key", in which case we
> internally create an anonymous keyset with just one key.

Done. The anonymous keyset takes the name of the interface.