switch master to 2.3-SNAPSHOT
=doc #3167 Image clarifying paths, incarnations, UIDs, ActorRefs and Selections.
Merge pull request #1611 from drewhk/wip-3167-illustration-actor-lifecycle-drewhk

=doc #3167 Image clarifying paths, incarnations, UIDs, ActorRefs
Merge pull request #1610 from akka/wip-2.3-SNAPSHOT-∂π

switch master to 2.3-SNAPSHOT
Merge remote-tracking branch upstream/$:{upbranch}