=str #15355: fix race with ExposedPublisher messaage in tee

 - this change makes the secondary subscription lazy
Merge pull request #15356 from spray/release-2.3-dev-http

akka-http-core
Merge pull request #15391 from spray/w/small-http-core-changes

+hco Small akka-http-core changes as a preparation for the Java API
Merge pull request #15367 from drewhk/wip-15355-tee-first-message-race-drewhk

=str #15355 Fix race in Tee causing a RequestMore overtaking ExposedPublisher
!str Extend StreamIO API with `idleTimeout` config setting, improve `connectTimeout` model (refs #15401)
!hco Add client-side request rendering and response parsing, refactor, strip-down

Remove everything that is out of scope for akka-http-core M1.
Things like the host- and request-level client-side API will be added back later.
=hco Remove `Low-Level API Design.rst`
+hco Java model for http-core
=hco Changes needed to compile with java 6 on mac