=doc 3764 revise recommended practice for Props creation

- it is not recommended to use Props.apply(=> Actor) within an Actor
- it is recommended to use that method in the Props factory method in
  an actor’s companion object
!act,doc,rem,tes 3823 remove deprecated Props methods

- rewrite deprecated usages to their recommended counterparts
- TestActorRef now verifies mailbox requirements
- CallingThreadMailbox now exposes proper messageQueue type for
  inspection
!pro,sbt #3781 Remove akka-sbt-plugin
!rem #3765: Change the defaults for remoting

 - removed retry-window and related settings
 - removed gate-invalid-addresses-for
 - gate is now mandatory
 - remoting has a dedicated dispatcher by default
 - updated tests to work with changed timings
 - added doc section for association lifecycle
!per #3704 Persistence improvements

- Channel enhancements (#3773):
- Live read models (#3776):
- Batch-oriented journal plugin API (#3804):
- Batching of confirmations and deletions
- Message deletion enhancements (more efficient range deletions)
Merge pull request #1886 from drewhk/wip-3765-change-remoting-defaults-drewhk

!rem #3765: Change the defaults for remoting
Merge pull request #1934 from akka/wip-3781-remove-sbt-plugin-patriknw

!pro,sbt #3781 Remove akka-sbt-plugin
!cha #3789: Remove typed channels
Merge pull request #1933 from akka/wip-3764-props-docs-∂π

clean up docs and deprecation around how to create Props
Merge pull request #1915 from krasserm/wip-3704-persistence-improvements-part-1-krassserm

!per #3704 Persistence improvement (part 1)
!act #3812: Remove Pipelines
=act #3738 Fix memory leaks in tests

* afterAll not called when all tests marked as ignore,
  invokeBeforeAllAndAfterAllEvenIfNoTestsAreExpected = true
  should solve that, but changed to pending in Ticket1978 anyway
* Try to shutdown when ActorSystem init fails. It is difficult
  to cover all scenarios, but this should improve the situation.
  This was the reason why DeployerSpec leaked.
* missing shutdown in some tests
Merge pull request #1932 from drewhk/wip-3812-remove-pipelines-drewhk

!act #3812: Remove Pipelines
Merge pull request #1931 from drewhk/wip-3689-remove-typed-channels-drewhk

!cha #3789: Remove typed channels
=act #3572 Add parens to sender

* because it is not referentially transparent; normally we reserved parens for
  side-effecting code but given how people thoughtlessly close over it we revised
  that that decision for sender
* caller can still omit parens
+act #3586 #3807 Implement mandatory read throttling
Merge pull request #1929 from akka/wip-3572-sender-patriknw

=act #3572 Add parens to sender
=per #3820 Increase some test timeouts in persistence

* reproduced the problem with sleep in LeveldbStore
Merge pull request #1909 from drewhk/wip-io-read-throtting-drewhk

+act #3586 #3807 Implement mandatory read throttling
Merge pull request #1937 from akka/wip-3820-persistence-test-timeouts-patriknw

=per #3820 Increase some test timeouts in persistence