4.0.0

Major changes to the underlying mechanism for coupling one connection to another without breaking the API. So while this is not technically a breaking change, it should be something that people opt into rather than get automagically upgraded to.

Primarily the logic rework has been done but breaking a large part of the coupling logic into a new package called rtc-taskqueue which uses a priority queue, readiness measures and incorporates validation logic (thanks to rtc-validator) to do everything we can to ensure that calls to the underlying RTCPeerConnection and associated types are applied in the right order.

In addition to the coupling logic changes, the generic monitor eventemitter has been replaced with a package called mbus that allows events to be communicated through a parent hierarchy giving us the ability to communicate efficiently from the internals of coupling logic to top level events as this functionality is integrated into other rtc.io packages.