HTTP request pipelining

[adamretter]

At the moment there is no support for HTTP 1.1 Request Pipelining. This might be a nice thing to think about in future.

See for example: https://hc.apache.org/httpcomponents-asyncclient-ga/httpasyncclient/examples/org/apache/http/examples/nio/client/AsyncClientPipelinedStreaming.java

[ChristianGruen]

Interesting idea. I decided to assign a new http-client-3 label here.

Support for HTTP/2 Multiplexing could be exciting as well (see e.g. https://stackoverflow.com/questions/34478967/what-is-the-difference-between-http-1-1-pipelining-and-http-2-multiplexing).