=htc Fix handling of non-BMP characters in URI encoding/decoding, closes #16014

Also improved the tests for this as they were sub-par so far
=str #16001 Propagate error to FoldSink's future

* align OnCompleteSink's implementation of error/success handling with
  that of other Sink's
Merge pull request #16006 from volkerstampa/wip-16001-foldsink-error-handling-volkerstampa

Propagate error to FoldSink's future. Fixes #16001
+htp #15910 import + improve coding infrastructure from spray
=str #15888: Fix unguarded access to input queue causing NPE
=htc Add test case for bind failures
!str #15977 Rename and change types in the new DSL

* Cleaned up type signatures
* Changed names of Source/Sink/ProcessorFlow to Tap/Drain/Pipe
* Introduced new Source/Sink/Flow
* Made all Pipe types package private
* Changed the TypeGraph DSL to work on Flow/Sink/Source
+hco #15798 add missing java api for Connection.tokens

Resolves #15798
Merge pull request #16024 from ktoso/wip-hco-java-api-connection-ktoso

+hco #15798 add missing java api for Connection.tokens
Merge pull request #16007 from akka/wip-15977-changin-all-the-small-dsl-things-ban

+str #15977 Rename and change types in the new DSL
=str #15874 Hook-up balance operation
Merge pull request #16025 from drewhk/wip-http-bind-failure-testcase-drewhk

=htc Add test case for bind failures
Merge pull request #16023 from drewhk/wip-15888-fix-unguarded-queue-access-ssl-drewhk

=str #15888: Fix unguarded access to input queue causing NPE
Merge pull request #15984 from spray/w/15910-encoding-infrastructure

+htp #15910 import coding infrastructure from spray
Merge pull request #16015 from spray/wip-16014-mathias

=htc Fix handling of non-BMP characters in URI encoding/decoding
+str #15946 Support flows without junctions in FlowGraph

* run simple flow with source/sink without any junctions in FlowGraph
* partial flow graph with undefined source/sink and flows, without junctions
* replace undefined source/sink with flow with source/sink
Merge pull request #16010 from akka/wip-15946-simple-flow-graphs-patriknw

+str #15946 Support flows without junctions in FlowGraph
Merge pull request #16013 from 2m/wip-hook-balance

=str #15874 Hook-up balance operation
+str #15905 Add capability to merge and connect flow graphs

* import edges of another flow graph to the builder
* connect undefined sink with undefined source, which may originate
  from different flow graphs
* illustrate how this low level api can be used in a high level api
  (lego bricks)