Support JupyterLab 2.0.0

[consideRatio]

I think this is a backward compatible change that makes the jupyterlab extension jupyterlab-plotly support JupyterLab 2.0.0 by accepting also JupyterLab 2.0.0 required dependencies.

Fixes #2244

JupyterLab 2.0.0 references

• Change log for developers
• A migration guide

[nicolaskruchten]

Thanks very much for this PR! I'll QA it today and if all looks good, release as well.

This is intended to be backwards-compatible in the sense that the extension should run in JupyterLab 1.2 as well, correct?

[consideRatio]

@nicolaskruchten you'r welcome =) Yes exactly, this jupyterlab extension it will installable with both JupyterLab 1 and 2. If we would remove the || parts in the package.json and only use the newer version, it would disrupt JupyterLab 1 users wanting to use the latest released version of the plotly-extension, as they would instead get the latest compatible version which would be those before this PR assuming it removed the || part.

I opted to have a || part to make JupyterLab 1 and 2 usable with any future releases of this extension and not only JupyterLab 2, as there will be various JupyterLab 1 users straggling that may want to use the latest releases coming seemingly quite often for the plotly-extension.

[consideRatio]

@nicolaskruchten I bumped the node package version of this npm package itself, I'm not sure if that made sense to do.

[nicolaskruchten]

Super, thanks for the clarifications. Bumping the package version is fine I think: normally I do it during the release process but I'll likely merge and release within a few minutes anyway so this is great :)

[nicolaskruchten]

OK this all looks awesome, I should be able to merge and release tonight after the kids are in bed (famous last words!)

I should add that it's always a real pleasure to head to work thinking "man, gotta deal with this new problem that cropped up" and to arrive to find a PR that fixes it, ready to go, so thanks again!

[nicolaskruchten]

This is now released! Unfortunately FigureWidgets don't appear to work in JLab 2.x... See #2249 for details if you're curious or have any ideas!