NumPy: Various updates

[hroncok]

No description provided.

[hroncok]

OK, this have started as a typo fix, and ended up by restarting the entire notebook.

I can later try to produce a nicer diff by emitting the image changes, as I don't believe they are important. However not today. Let me know if I shall.

Can be previewed at https://naucse.python.cz/2019/mipyt-zima/intro/numpy/

[hroncok]

Nota bene:

• The example with 49.799999999999997 is now corrected to 49.8 by NumPy (or Python?). I've cheated and edited it back manually.
• There is a new deprecation warning (The truth value of an empty array is ambiguous...). I've manually edited the warning not to include my venv path. Also, it seems like we miss some CSS styles for those.

[encukou]

Looks good! Thanks!
FWIW, I diffed using nbdiff, specifically:

$ nbdiff-web \
    <(git show master:lessons/intro/numpy/index.ipynb) \
    <(git show HEAD:lessons/intro/numpy/index.ipynb)

[encukou]

The issues you found don't look critical, but could you open issues for them?

[hroncok]

pyvec/naucse#27

[hroncok]

#565

[encukou]

Thank you!

[hroncok]

Thanks for the nbdiff-web tip!