What does this implement/fix? Explain your changes.

Implements

• python setup.py build_dotnet --inplace
• python setup.py develop
• pip install -e .

This allows for easier development, it should now be enough to run on of
these for changes to the .NET code.

Does this close any currently open issues?

Helps with #1316.

Any other comments?

...

Checklist

Check all those that are applicable and complete.

• Make sure to include one or more tests for your change
• If an enhancement PR, please create docs and at best an example
• Add yourself to AUTHORS
• Updated the CHANGELOG