Support pyproject.toml

[davidcavazos]

It would be great to have support for pyproject.toml files. This is the new official way to specify PyPI packages as described in PEP-621, recommended over setup.py and setup.cfg files.

Being a simple TOML file, it should be pretty straightforward to parse and write with the toml package. It could also be easily extended to other metadata formats.

For PEP-621 pyproject.toml

• [project.dependencies]
• [project.optional-dependencies]

For Poetry pyproject.toml

• [tool.poetry.dependencies]
• [tool.flit.metadata.requires-extra]

For setup.cfg file

• [tool.flit.metadata.requires]
• [tool.flit.metadata.requires-extra]

For old style Flit flit.ini file

• [tool.flit.metadata.requires]
• [tool.flit.metadata.requires-extra]