Objects that go out of memory still receive events

[Janglinator]

We should retain a weak reference to ids if they're objects, so we can monitor when they go out of memory, and automatically unsubscribe them.

[Alarson93]

I had considered building something like this previously, but couldn't figure out how to best check if an object was still in memory.

Looking back on it now, I think it is smelly. Our library is trying to clean up a mess that something else has created. I think it would be best practice for subscribing objects/instances to clean their own messes up. We can easily unsubscribe from a deinit method.