- add Logging trait for nicer interface
- add EventHandlerLogging class for offering the nice interface from
app.log
- add eventHandler instance to app and use that for all internal logging
(this means that some places (dispatchers, remoting) were infiltrated
by app just to do logging, but I think we'll need app in there soon
enough for other reasons)
- removed SelfActorRef
- added an ActorContext interface that provides a view into ActorInstance
- the ActorInstance (as ActorContext) gets injected into the Actor
- moved self methods like sender and reply directly to the Actor
- removed transactors everywhere
- moved stm into akka-stm module
- disabled agents (they use transactors internally)
- rewrote persistence tests so that they don't use transactors