Prepare for 0.4.0.M1

Docs tweaking and package info renaming in README.md
> Canceling a Subscription has no influence on the Publisher accepting or continuing subscriptions with other Subscribers/Subscriptions.

In Rx a hot connectable observable with refCount() does cancel the data-source after all active subscribers have unsubscribed, in which the data source is whatever is producing data - a periodic task executed by a scheduler, an actor, a web socket connection, whatever. For such a scenario, it depends on the Publisher implementation on what it is supposed to do after a new subscriber comes along - does it emit onComplete? Does it start the data-source again? And if the data-source is restarted, it may produce different data that if the old data-source was never canceled.

So why shouldn't a Subscription.cancel() be allowed to have an effect on current or future subscribers? That's an unjustified limitation.