Tidy up imports

[EarlMilktea]

Description of the change:

• Use coherent import style
• Add coverage ignore patterns
• Prohibit relative import
• Resolve deeply-nested import that will lead to mypy warning

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 91.56627% with 7 lines in your changes missing coverage. Please review.

Project coverage is 78.10%. Comparing base (b60ff8b) to head (1def5cb). Report is 1 commits behind head on master.

Files with missing lines	Patch %	Lines
graphix/gflow.py	84.84%	5 Missing :warning:
graphix/generator.py	50.00%	1 Missing :warning:
graphix/pattern.py	50.00%	1 Missing :warning:

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #217      +/-   ##
==========================================
+ Coverage   77.42%   78.10%   +0.68%     
==========================================
  Files          38       38              
  Lines        6166     6007     -159     
==========================================
- Hits         4774     4692      -82     
+ Misses       1392     1315      -77     

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[EarlMilktea]

could you also improve imports in examples or do you think we can leave them like they are?

We could safely leave them untouched after adding __all__ attributes.

[EarlMilktea]

Or we may remove all the imports in __init__.py ?

Which do you prefer?

[shinich1]

Or we may remove all the imports in __init__.py ?

Which do you prefer?

thanks, adding __all__ would be good I think.

[EarlMilktea]

@thierry-martinez

Could you review this PR? I would like to work on refactoring pauli.py after this PR.

[EarlMilktea]

@thierry-martinez Reminder