Receiving messages in multiple tabs

[caolan]

If you open the same app instance in multiple tabs or browser windows, they will race each other to handle incoming messages. There's no particularly nice universal way to resolve this as it depend on what the messages are being used for.

For now, it might be worth restricting subscriptions to a single mutiny-app client (browser window/tab) at a time.

[caolan]

Locking in general might be the easiest way to handle this. Performance is not a huge concern as we're likely serving a single local user. Adding some kind of transaction API for any mutinyd reading/writing might be a general purpose solution?