Run in Jupyter labs as well as REPL

[leerosenthalj]

Would it be straightforward to enable Cthulhu to run in Jupyter lab/notebook environments as well as the REPL? It would be great to be able to use Cthulhu in Jupyter as a testing environment.

[vchuravy]

As said on slack, someone would need to write a html widget that works in Pluto or Jupyter.

Alternativly we could improve the non-interactive functions to expose the new typed source view.