* CoordinatedShutdown that can run tasks for configured phases in order (DAG)
* coordinate handover/shutdown of singleton with cluster exiting/shutdown
* phase config obj with depends-on list
* integrate graceful leaving of sharding in coordinated shutdown
* add timeout and recover
* add some missing artery ports to tests
* leave via CoordinatedShutdown.run
* optionally exit-jvm in last phase
* run via jvm shutdown hook
* send ExitingConfirmed to leader before shutdown of Exiting
to not have to wait for failure detector to mark it as
unreachable before removing
* the unreachable signal is still kept as a safe guard if
message is lost or leader dies
* PhaseClusterExiting vs MemberExited in ClusterSingletonManager
* terminate ActorSystem when cluster shutdown (via Down)
* add more predefined and custom phases
* reference documentation
* migration guide
* problem when the leader order was sys2, sys1, sys3,
then sys3 could not perform it's duties and move Leving sys1 to
Exiting because it was observing sys1 as unreachable
* exclude Leaving with exitingConfirmed from convergence condidtion
Need this for AtLeastOnceDelivery
Messages marked with `NotInfluenceReceiveTimeout` will not reset the timer.
This can be useful when `ReceiveTimeout` should be fired by external inactivity
but not influenced by internal activity, e.g. scheduled tick messages.
add to rst docs also
* deprecates awaitTermination, shutdown and isTerminated
* introduces a terminate-method that returns a Future[Unit]
* introduces a whenTerminated-method that returns a Future[Unit]
* simplifies the implementation by removing blocking constructs
* adds tests for terminate() and whenTerminated
* Added a setter for Java lambda actors to "hide" the not so nice looking type signature of the "receive" method.
* Updated docs to reflect the changes.
* Converted samples to use the new setter.
* The Java with Lambda support documentation for AbstractActor and AbstractFSM are now on par with Scala
* Many small fixes and additions of missing things
* Added an AbstractActorContext that has convenience functions for getChild and getChildren
