+con #3677 Limit delta in DistributedPubSubMediator
!con #3679 Make protobuf serialization for DistributedPubSubMediator
=doc #3682 Document message size limit in SslTlsSupport.
=clu #3683 Don't trigger extra heartbeat when not expected sender
=act 3571 quiet down exceptions from `Socket.shutdownOutput()`

Backport from this spray commit:

https://github.com/spray/spray/commit/e4068046a5a501b059e0cf9305a85f9c1aca7e42
update to latest version of Typesafe CONTRIBUTING rules
=act 3684 prevent usage of WriteCommands other than Tcp.Write with SslTlsSupport
Merge pull request #1798 from akka/wip-3682-document-message-size-limit-in-ssltlssupport-ban

=doc #3682 Document message size limit in SslTlsSupport.
Merge pull request #1804 from jrudolph/i/3684/prevent-WriteFile-CompoundWrite-in-ssl

=act 3684 prevent usage of WriteCommands other than Tcp.Write with SslTlsSupport
Merge pull request #1800 from jrudolph/i/3571/fix

=act 3571 quiet down exceptions from `Socket.shutdownOutput()`
=doc #3684 Document that SslTlsSupport doesn't support Tcp.WriteCommand.
Merge pull request #1809 from akka/wip-3684-ssltlssupport-do-not-support-tcp-writecommands-ban

(forward port) =doc #3684 Document that SslTlsSupport doesn't support Tcp.WriteCommand.
Merge pull request #1792 from akka/wip-3677-limit-delta-patriknw

+con #3677 Limit delta in DistributedPubSubMediator
Merge pull request #1812 from akka/wip-3679-protobuf-pubsub-patriknw

!con #3679 Make protobuf serialization for DistributedPubSubMediator
Merge pull request #1799 from akka/wip-3683-extra-heartbeat-patriknw

=clu #3683 Don't trigger extra heartbeat when not expected sender
=doc Fix spelling. Change depreceated to deprecated
Merge pull request #1811 from benmccann/depreceated-spelling

=doc Fix spelling. Change depreceated to derecated
Merge pull request #1803 from akka/wip-CONTRIBUTING-∂π

update to latest version of Typesafe CONTRIBUTING rules
!per #3681 Performance and consistency improvements

- batch-write of persistent messages (user API)
- batch-write of events (in EventsourcedProcessor)
- command processing in EventsourcedProcessor by unstashing messages one-by-one from the internal stash
   * fixes performance issues that come up with unstashAll
- commands are not looped through journal actor but processed directly
- initial performance tests
  * command sourcing
  * event sourcing
  * event sourcing with user stash operations
- suppress stack traces in tests
Merge pull request #1808 from krasserm/wip-3681-performance-improvements-krasserm

!per #3681 Performance and consistency improvements