Setuptools integration

[takluyver]

@jbaiter wrote on PR #13:

"""
I'm currently preparing to ship spreads for Windows. The software makes heavy use of the Python packaging ecosystem for its plugin discovery, so I had to work around some small issues with pynsist to get it to package all of the .egg-info and .dist-info files/directories. You can take a look at the script that builds the MSI installers to see how I'm currently using pynsist from code: https://github.com/jbaiter/spreads/blob/windows/buildmsi.py

It would be great if setuptools/pkg_resources integration could be put on the roadmap, I think that's a feature that would benefit a lot of people and the ecosystem as a whole.
"""

@jbaiter's script finds and copies the egg-info/dist-info bits separately from the actual packages. I'm not sure at present whether it's easier to do that, or to treat 'distributions' as a different kind of thing, which include that info along with a number of packages.

[adferrand]

Something that could be closed as #161 is merged?

[takluyver]

Yup, thanks.

For people finding this in the future: Pynsist supports the standardised .dist-info metadata from wheel packages. I have no plans to support setuptools' pre-standardisation 'egg' formats.