ipywidgets 6.0 release plan

[Jason Grout]

FYI for those that are interested - we're closing in on an ipywidgets 6.0, widgetsnbextension, and jupyter-js-widgets RC/release cycle. We've opened https://github.com/ipython/ipywidgets/issues/1116 to track the release process.

We hope to have the outstanding GitHub issues resolved today, and hope to cut a final beta or RC 1 in the next day or two.

Thanks,

Jason