Complete supervision semantics

[rogeralsing]

Go has supervision, but we need to set the semantics around this.

[rogeralsing]

I propose that we make a new interface ChildRestartStatistics and let the context or some child object implement this interface.
GAM does not support remote supoervision, so we can simply ignore any cross process aspects here.

In Akka, the child container is responsible for keeping track of child restart stats.
We could simply let each actor keep track of their own restarts passing the ChildRestartStatistics interface of themselves to their parent supervisor.

This means that each Failure message would also contain the ChildRestartsStatistics instance. making it possible for the SupervisorStrategy to act upon that.
This instance could be immutable, and we could update it only once the child is restarted. thus sharing nothing.

[rogeralsing]

[rogeralsing]

This has been merged