=str #16026 Emit directly in MapAsyncProcessor and MapAsyncUnorderedProcessor
=str #16040 Use scaladsl2 in TCK tests

* found and fixed one issue: onError was invoked twice for the overflow
  error
* and also noticed that we restart the actors, instead of stopping them
  in case of internal error, changed to stopping strategy
+str #15998 Add Source singleton, empty, failed factories
Merge pull request #16043 from akka/wip-16026-patriknw

=str #16026 Emit directly in MapAsyncProcessor and MapAsyncUnorderedProcessor
Merge pull request #16044 from akka/wip-16040-tck-scaladsl2-patriknw

=str #16040 Use scaladsl2 in TCK tests
Merge pull request #16045 from akka/wip-15998-basic-Source-factories-patriknw

+str #15998 Add Source singleton, empty, failed factories
!htc #15726: Akka HTTP with the new DSL
Added some sugar
ported rest of Http
big FlowMaterializer removal