http-client-branch: fix HTTP/1.1 retry to avoid duplication of header values

Merge

http-client-branch: minor cleanup in HttpRequestImpl

http-client-branch: verify that send/sendAsync will throw IAE and NPE as specified by HttpRequest.Builder

http-client-branch: (WebSocket) from IOE to IAE in sendClose with bad reason

http-client-branch: supplementary review comments

http-client-branch: missing <p>

http-client-branch: API note about sendPong

http-client-branch: (WebSocket) almost missed the CSR train

http-client-branch: Early Review comments for JDK-8199938 Supplementary minor HTTP Client spec clarifications

http-client-branch: bye, bye, SSLDelegate

http-client-branch: (WebSocket) javadoc typos

http-client-branch: (WebSocket) remove notion of partial/parts/whole messages (RFC 6455 says text and binary can be streamed unrestricted); introduce pending send operations to refer to them later in about and sendText/sendBinary

http-client-branch: typo

http-client-branch: (WebSocket) alleviated heavy use of {@code WebSocket} in the javadoc; more details on Listener methods

http-client-branch: minor HttpClient.send exception correction

http-client-branch: minor WebSocket.Listener re-wording

http-client-branch: (WebSocket) API wording for back-pressure

http-client-branch: (WebSocket) remove close timer

http-client-branch: RawChannel implementation based on FlowTube

http-client-branch: (WebSocket) split pending operations tests, otherwise it took them too long to run

http-client-branch: (WebSocket) full-duplex DummyWebSocketServer; tests stabilization & fixes

http-client-branch: (WebSocket) autopong on a closed channel is not an error + test

http-client-branch: (WebSocket) no error after abort

http-client-branch: (WebSocket) abort tests

http-client-branch: (WebSocket) removed MessagePart

http-client-branch: (HttpClient) faulty assertion, some tests fail

http-client-branch: (WebSocket) API changes + test;