* Add unit tests for core::nodes::NodeStream
* Move DummyMuxer to core/tests
* Address grumbles
* Impl Debug for SubstreamRef<P>
* Add test for poll()
* Don't need to open a substream
* pretty printer test
* More tests for NodeStream poll()
* ListenerStream unit tests: transport() and listeners()
* Tests for nodes/listeners.rs
* Add a few tests to help illustrate the "drowning" behaviour of busy listeners
* Address grumbles
* Remove non-project specific stuff
* Address grumbles
* Prefer freestanding function
* Add circleci config file
* Try enable IPv6
* Make sure `test` uses machine executor
* Add an integration_test step in parallel
* Explicit docker runs for machine tests
* Try make the integration test work
* Hide Dockerfile in a subfolder
* Fix the ping example hanging
* Explicitely pass the port to the ping client
