!str #15742 Hook-up groupBy to new DSL

* Produces Flows instead of Publisher
!str #15742 Hook-up prefixAndTail to new DSL

* Produces tail with flows instead of Publisher
!str #15742 Hook-up splitWhen to new DSL

* Produces flows instead of publishers
!str #15742 Hook-up flatten (concat all) to new DSL

* input streams of flows, instead of publisher
=str #15740 hookup filter and collect

* copy tests from old DSL
* adapt ChainSetup to the new DSL
=str #15735 Prototype of FlowGraph

Add documentation
Merge pull request #15805 from akka/wip-15735-flow-graph-research-patriknw

Prototype of FlowGraph
Merge pull request #15834 from 2m/wip-hook-filter-collect

=str #15740 hookup filter and collect
Merge pull request #15824 from akka/wip-15742-flow-of-flows-patriknw

!str #15742 Hook-up flow of flows to new DSL
=str #15739 Hook-up grouped, groupedWithin, timerTransform to new DSL
=str #15738 Hook-up drop, dropWithin, take, takeWithin to new DSL
=str #15741 Hook-up conflate, expand, buffer, and FoldSink
Merge pull request #15838 from akka/wip-15739-15738-15741-patriknw

=str #15739 #15738 #15741 Hook-up more ops to new DSL
=str #15402 Split up MultiStream(Input|Output)Processor since SSL will use both
+str #15402 SSL support for streams
Merge pull request #15806 from akka/wip-15402-ssl-tls-io-ban

+str #15402 SSL support for streams (working for happy case)
=pro #15849 fix scala-graph dependency for building for Scala 2.11
=pro use idiomatic sbt for including post-scala-2.10 dependencies

This re-enables using `++ 2.11.2` in sbt for quick changing of Scala versions.
=pro upgrade macro paradise dependency to 2.0.1 (to allow building for Scala 2.11.2)