2.0.0rc0

This version uses async-kernel extensively.

Everything works reliably for a single user/browser interface.

Only source is provided so that specific dependencies can be included:

Name	Pull request	Status	Modification
traitlets	#918	Accepted - pending release	Improved type hints
ipywidgets, jupyterlab-widgets, widgetsnbextension	#3922 + #3921	Pending review	Provides for widgets comms without needing a notebook or console to be open. Plus fixes for proper garbage collection and widget tooltips
jupyter_client	#1064	Pending review	Faster message serialization

pip install from source to install.

Full Changelog: v2.0.0b5...v2.0.0rc0