[Distutils] wheel setup.cfg extensions

[Daniel Holth]

Where should these go / be defined?

The wheel project understands some setup.cfg extensions that are
important for Metadata 2.0 and wheel. The [metadata] section allows
you to override the setup(install_requires=[...]) with values
containing environment markers.

[metadata] also lets you specify a LICENSE.txt to be copied into the
.dist-info directory (not mentioned in METADATA) just so the resulting
wheel is less likely to violate the common "include the license with
all copies of this software" restriction.

The [wheel] section lets you instruct bdist_wheel to tag your wheel as
a universal wheel.

[metadata]
provides-extra =
    tool
    signatures
    faster-signatures
requires-dist =
    distribute >= 0.6.30
    argparse; python_version == '2.6'
    keyring; extra == 'signatures'
    dirspec; sys.platform != 'win32' and extra == 'signatures'
    ed25519ll; extra == 'faster-signatures'
license-file = LICENSE.txt

[wheel]
universal=1 # use py2.py3 tag for pure-python dist