What's new:
Scala 2.13.0 support, except kafka-distributed-processing (see #75)
Eventsourced state fold is factored out to it's own data type Fold (#67):
EventsourcedBehavior(actions, init, update)becameEventsourcedBehavior(actions, Fold(init, update))EventsourcedBehavior.optional(actions, init, update)became `EventsourcedBehavior(actions, Fold.optional(init)(update))...