I modified the `CompositeObservable` to be backed ...

# tornadofx

[thomasnield]

I modified the CompositeObservable to be backed by a Subject instead. Adding an Observable source to it will yield a Subscription, which you can call unsubscribe() at any time to stop sending emissions. I think this will effectively decouple Observables and Subscribers throughout models, views, controllers, etc whatever your setup is, and allow removal at any time.