Add AppVevor build for Windows support

[decentral1se]

https://www.appveyor.com/

We should probably do that. I see a number of issues reported on the windows platform.

This CI build might smoke out anything stupid we might do :)

[schlenk]

CI on Windows would be a nice to have.

I would not call it essential, as most parts of the code stay far away from the APIs where the differences matter, but some Linux based assumptions are broken on windows, and we might catch a few of those.

The setup doesn't run as smooth as it does on Linux, due to missing prebuilt dependencies.
pyldap isn't available as wheel on pypi, and building it needs quite a few dependencies, so i usually grab the prebuilt ones from the Gohlke site, but that cannot simply be added as a repository for pip. So basically download, add proper environment vars so pip picks it up from a local dir, and it works.

[decentral1se]

Hmmmm, sounds tricky. Well, you might be the person for this @schlenk!

Otherwise, I'll give it a stab when I get some time.

[tpazderka]

I tried this and I ran into the issue with pyldap. I don't like the idea f having some other library in the repository just because we need it to build on windows.

[decentral1se]

That's great @tpazderka - I think that would be fine, no? If it is clear, and separated in some way. The benefit of having this aspect of the CI would definitely help us catch issues on Windows easier. Can you share the build and error you were seeing?

[tpazderka]

It can be seen here.

I don't particularly like it since it adds some extra stuff to the repo that is not needed. Although we can probably exclude it from setup and such I would rather try a different way.

[schlenk]

I think it would be fine if we could isolate the ldap needing tests, and skip them for windows. After all, thats not the main usecase and for many cases the pyldap dependency is strictly optional.

There simply is no Windows whl for pyldap on pypi, but there are .whl's found here: https://www.lfd.uci.edu/~gohlke/pythonlibs/ but those pages are deliberately styled so you cannot simply use them to install directly with PIP.

So one way would be to use requests to just download a pyldap.whl from there, cache it locally and have pip use the whl from a local directoy.

[tpazderka]

Well those pages have obfuscated download links so the download might be real pain. I do like the idea of pyldap being an optional dependency and marking that as extra in the setup.

I will try to focus on that.