FEAT(GUI): Hierarchical column header view

[tmichela]

Adds hierarchical columns header view, to improve visually grouping Variables that belong together.

Hierarchy is built from variable's title: each '/' character splits the title to the next level.
Will be more important once #478 is merged.

[codecov]

Codecov Report

❌ Patch coverage is 86.37993% with 38 lines in your changes missing coverage. Please review.
✅ Project coverage is 79.20%. Comparing base (93a2b3d) to head (4bd133d).
⚠️ Report is 77 commits behind head on master.

Files with missing lines	Patch %	Lines
damnit/gui/table.py	85.49%	37 Missing ⚠️
damnit/gui/main_window.py	95.83%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #520      +/-   ##
==========================================
+ Coverage   78.84%   79.20%   +0.35%     
==========================================
  Files          37       37              
  Lines        6562     6829     +267     
==========================================
+ Hits         5174     5409     +235     
- Misses       1388     1420      +32     

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[takluyver]

The screenshot looks pretty nice. 👍 Do we want to impose some kind of sanity limit on the hierarchy depth? Or just trust people to be sensible with it?

There's quite a bit of detailed Qt code here using APIs that I'm not familiar with. Do you want to do a pair review in the new year? Or I'm happy to trust you on it, but maybe if we do that we should make an off switch to quickly go back to simple table headings in case of bugs (and then make a note to get rid of it in a few more months).

[tmichela]

Do we want to impose some kind of sanity limit on the hierarchy depth? Or just trust people to be sensible with it?

I would trust people will be sensible 🙃 I don't really think it will ever go over 2 levels to be honnest.

Do you want to do a pair review?

Not sure this is actually that useful, TBH. It's not impossible there's a bug in the sizes calculation, but I wouldn't be able to spot that by reading the code 🙃
Maybe you could try the feature, see if it breaks. I've done that extensivelly but others may try things I haven't thought about.

we should make an off switch to quickly go back to simple table headings in case of bugs

Good point, I just pushed that option.

[JamesWrigley]

Apologies, I completely missed this 😳 Will take it for a spin today.

[JamesWrigley]

Very shallow review. I tested it manually and it seems to work very nicely ✨

[JamesWrigley]

LGTM!

(but pls squash merge or rebase 🙏 )

[tmichela]

Thanks for the reviews!