notebook: support delay

[peterdhansen]

If you specify a delay in a jupyter notebook, the bar will always display regardless.

This PR will also delay the display command until the first update, unless display=True.

[codecov]

Codecov Report

Merging #1142 (8a66f6e) into devel (a162d02) will decrease coverage by 0.31%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##            devel    #1142      +/-   ##
==========================================
- Coverage   89.40%   89.08%   -0.32%     
==========================================
  Files          25       25              
  Lines        1651     1658       +7     
  Branches      273      275       +2     
==========================================
+ Hits         1476     1477       +1     
- Misses        129      132       +3     
- Partials       46       49       +3     

[peterdhansen]

I only see one test for tqdm notebook. I'm not sure how to add a test to cover this new logic.

[casperdcl]

Notebook isn't tested (yet) but I should probably change that soon :)

[casperdcl]

@peterdhansen I've rebased and added tests, as well as fixed the implementation bugs. Let me know if it works for you now.

[peterdhansen]

Looks good to me. I tried out the new test notebook and looks like it works as intended