Please publish a source distribution on PyPI & add a MANIFEST.in to the repo

[d-cunningham]

Hello, I am not reporting a bug, just have two simple requests. Could you add a MANIFEST.in to the repo (In reference to https://packaging.python.org/guides/using-manifest-in/)? In addition, wheel formats are great but downstream packagers rely on source distribution to create packages. Could you consider publishing the source distribution to PyPI along with the wheel? Both of these additions should make it easier for downstream packagers.