Sign language aside, which is a language, I think that things like gestures and smileys are communication systems, but they aren't full fledged language systems in that they do not allow the full range of human communication. It would be very frustrating to have to communicate only through smileys, and I doubt that I could manage an unreal past armed onlt with ASCII art. I think we're agreed on what they are, just give them slightly different terms.
