Moved the metadata into PEP 621-compliant sections.

[KOLANICH]

Since poetry has not yet implemented PEP 621 I have temporarily switched the build backend to flit. To use setuptools one has to comment out the lines choosing flit and uncomment the lines choosing setuptools. setup.py and setup.cfg have been removed, their content has been integrated into pyproject.toml.

PEP 621 support in poetry is tracked here: python-poetry/roadmap#3

[barrust]

Thank you for this PR, this looks great.

My one question is why flint over setuptools? I haven't used flint myself so I just wondered if there was a reason to use it as the default.

[KOLANICH]

flint

Not flint, but flit. In fact, flit_core.

My one question is why flit over setuptools?

I thought that if you wanted to use setuptools, you would have used it already, since it is the way the most of packages use and the kinda official successor of distutils.

I haven't used flit myself

There is a chance you had to use it. With PEP 517 the packaging has become mess with lot of build backends instead of setuptools. So I have to have all the three, setuptools, poetry_core and flit_core. Even some official packages by pypa depend on flit_core for their building, and flit_core depends on them itself, so if want to install evsrything from scratch and not to use any prebuilt wheels, we have to use hacky shell scripts.

Only with implementing PEP 621 in both flit_core and setuptools all this mess has started to clean up.

so I just wondered if there was a reason to use it as the default.

No reason, can switch to setuptools. The most prominent advantage of flit_core I have managed to feel is that it works much faster then setuptools. But I guess it may have come at cost.