Rewrite nbtutor code

[lgpage]

Todo:

• Update CI
• Fix lines not redrawing on toggle visualization
• Redo usage.gif
• Update log level (suppress debug)

Close #43

[lgpage]

Hi @Naereen
If you have some time free, mind giving this a once over and maybe a try your side :)
The DEVELOP.md file should be update to date to explain how to get it up and running locally, if not please let me know and I can fill in the gaps or make things clearer

[codecov]

Codecov Report

❗ No coverage uploaded for pull request base (master@88f6cc5). Click here to learn what that means.
The diff coverage is n/a.

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[Naereen]

Hi @Naereen
If you have some time free, mind giving this a once over and maybe a try your side :)
The DEVELOP.md file should be update to date to explain how to get it up and running locally, if not please let me know and I can fill in the gaps or make things clearer

Hi there.
I see that this file talks about Angular and other things like this, to be honest I won't have time to download and install the requirements to build the extension locally.

But by using a setup.py file here on GitHub, it's possible to install a pip package which is not yet updated on pypi.org, by using

pip install git+https://github.com/lgpage/nbtutor/

If you want I could try to do this (in a virtualenv) when your next version seems ready, but before you deploy it to Pypi.