Add universal wheel support

[jdufresne]

Wheels are the new standard of python distribution.

For detailed information, see PEP 427.

For high level information, see: https://pythonwheels.com/

Advantages of wheels

• Faster installation for pure Python packages
• Avoids arbitrary code execution for installation (avoids setup.py)
• Allows better caching for testing and continuous integration
• Creates .pyc files as part of installation to ensure they match the python interpreter used
• More consistent installs across platforms and machines

As this package is pure Pythong (no C files), I have marked the wheel as universal.

When you'd normally run python setup.py sdist upload, run instead python setup.py sdist bdist_wheel upload.

[vlasovskikh]

@jdufresne Thank you for updating your pull requests. I'm now considering switching from setuptools to Poetry, so some of the changes in your PRs may not be necessary. See my PR #61, feel free to review it, if you're interested :)

[vlasovskikh]

@jdufresne I switched from setuptools to poetry, so wheels are now created automatically by poetry build.