Support JupyterLab 3

[nrbgt]

It's worth a look to see which (if any) of the upstreams haven't been released to support lab3. Going to 3 would remove node/npm entirely from this repo for everything except prettier, which we can vendor, and would improve both development time and potentially CI.

real dependencies

extension	status	link
@jupyter-widgets/jupyterlab-manager	ready	https://pypi.org/project/jupyterlab-widgets/1.0.0/
@pyviz/jupyterlab_pyviz	ready	https://pypi.org/project/pyviz-comms/2.0.1/
jupyter-cytoscape	ready	https://pypi.org/project/ipycytoscape/1.2.0/
qgrid2	dead	---

what to do about qgrid

• alternatives
  • ipyregulartable
    • support merged, probably releasing real soon now
  • wxyz-datagrid
    • not started yet

dev/docs dependencies

extension	status	link
@deathbeds/jupyterlab-drawio-notebook@0.8.0-alpha1	not started	https://github.com/deathbeds/jupyterlab-drawio/issues/11
@deathbeds/jupyterlab-drawio-webpack@13.6.2-alpha1	not started	https://github.com/deathbeds/jupyterlab-drawio/issues/11
@deathbeds/jupyterlab-drawio@0.8.0-alpha1	not started	https://github.com/deathbeds/jupyterlab-drawio/issues/11

[zwelz3]

Is this closed by #69 ? I know we added JL3 in the README, but I'm not sure if that means everything is properly supported.

[zwelz3]

After speaking with @sanbales we are going to bump ipyradiant to JL3 and pin cytoscape >=1.2.0.

qgrid is no longer a hard dependency (although some mentions still exist in README), so we shouldn't have any issue with upstreams.