Dynamic line rating

[FabianHofmann]

Closes #131

Major Changes

1. A new intersection matrix function was added, which works similarly to incidence matrix but has boolean values.
2. Wind retrieval now also computes the wind direction given by the azimuth in radians. Note that this does not require to download additional variables, thus it hardly affects the computing time.
3. Line rating and line ratings conversion functions were added based on the IEEE-738 standard, with small modifications
4. Tests against the IEEE sample case and two others were added.

Type of change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist

• I tested my contribution locally and it seems to work fine.
• I locally ran pytest inside the repository and no unexpected problems came up.
• I have adjusted the docstrings in the code appropriately.
• I have documented the effects of my code changes in the documentation doc/.
• I have added newly introduced dependencies to environment.yaml file.
• I have added a note to release notes doc/release_notes.rst.
• I have used pre-commit run --all to lint/format/check my contribution

[codecov-commenter]

Codecov Report

Merging #189 (45aa236) into master (0b2c19c) will increase coverage by 0.99%.
The diff coverage is 96.10%.

@@            Coverage Diff             @@
##           master     #189      +/-   ##
==========================================
+ Coverage   74.15%   75.15%   +0.99%     
==========================================
  Files          18       18              
  Lines        1366     1441      +75     
  Branches      183      189       +6     
==========================================
+ Hits         1013     1083      +70     
- Misses        291      294       +3     
- Partials       62       64       +2     

Impacted Files	Coverage Δ
atlite/convert.py	80.95% <94.73%> (+5.13%)	⬆️
atlite/cutout.py	72.53% <100.00%> (+0.43%)	⬆️
atlite/datasets/era5.py	86.95% <100.00%> (+0.19%)	⬆️
atlite/gis.py	91.16% <100.00%> (-0.40%)	⬇️
atlite/wind.py	72.22% <100.00%> (+1.63%)	⬆️

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