Stop sendin isTyping event when no actual typing is happening

[mattmezza]

If you press "alt" it handles it as a typing event, so when you alt+tab out of the browser, it's as if you were typing. I believe a typing event should happen when an actual character is typed.

Originally opened in #104.

[Berkmann18]

That and/or a way to send STOP_TYPING/NOT_TYPING events which are useful when coupling this with a SocketIO chat.