* 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
* Provide poll() as a regular method when we can't fail
* Add a CollectionReachEvent that allows accepting
* Add small TODO in handled_node
* Implement Debug on collection events
* Implement Debug for CollectionStream
* Implement Debug for structs in handled_node_tasks
* Attempt to fix compilation errors with stable Rust
* Prove the unwrap