Moved the metadata into setup.cfg

[KOLANICH]

Added pyproject.toml
Version is now populated automatically from git using setuptools_scm.

I had to remove everything from meta except the version (it can be fetched and populated, but it will slow down loading the module and I really doubt anyone ever relied on this API) and also removed the very suspicious exec call that has no legit reason to be present in this lib.

[alexmojaki]

+1 for removing exec, see #87

I quite like the setup in my own packages like https://github.com/alexmojaki/executing which was also initially introduced by @KOLANICH. It's minimal and very standard, see e.g. setup.py. @gruns are you attached to the commands in your setup.py? For publishing I use https://github.com/alexmojaki/executing/blob/master/make_release.sh. Is being able to run python setup.py test important?

[KOLANICH]

@alexmojaki, BTW you should be able to remove setup.py completely since modern versions of pip support editable install in this case. I also think that we should get rid of setup.py here too.

[Jakeroid]

@KOLANICH

Thank you for any support from your side. Do you think it would be possible to resolve conflicts and prepare a PR to move forward in a future without setup.cfg?