Added generic extensions to EventStream subscribe/unsubscribe.

[nvivo]

EventStream is one of the few pieces that don't have generic counterparts.

This patch allows for:

EventStream.Subscribe<SomeMessage>(Self);
EventStream.Unsubscribe<SomeMessage>(Self);

instead of

EventStream.Subscribe(Self, typeof(SomeMessage));
EventStream.Unsubscribe(Self, typeof(SomeMessage));

I was going to add these methods directly to EventStream, but it seems these generic versions are usually extensions methods. One caveat with the extension method is that most code don't require an using Akka.Event, so people may miss it entirely.

Please let me know if they should be moved.

[rogeralsing]

Looks good to me 👍

[Aaronontheweb]

One caveat with the extension method is that most code don't require an using Akka.Event, so people may miss it entirely.

Is the EventStream in the Akka.Event namespace too?

[rogeralsing]

Yes

[Aaronontheweb]

Cool - I think that should be fine then.