=act #3601 Harden test for log dead letters
=act,rem #3073 Make ActorSelection faster
Merge pull request #1813 from akka/wip-3073-faster-actorselection-patriknw

=act,rem #3073 Make ActorSelection faster
Merge pull request #1820 from akka/wip-3601-ActorSystemSpec-patriknw

=act #3601 Harden test for log dead letters
Merge remote-tracking branch: upstream/master