Feature/co2 emission coefficients

[Bachibouzouk]

Fix #950, fix https://github.com/open-plan-tool/gui/issues/59

Changes proposed in this pull request:

• Your_changes

The following steps were realized, as well (if applies):

• [ ] Use in-line comments to explain your code
• [ ] Write docstrings to your code (example docstring)
• [ ] For new functionalities: Explain in readthedocs
• [ ] Write test(s) for your new patch of code (pytests, assertion debug messages)
• [ ] Update the CHANGELOG.md
• [ ] Apply black (black . --exclude docs/)
• [ ] Check if benchmark tests pass locally (EXECUTE_TESTS_ON=master pytest)

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