Add support for Python 3.6 and Python 3.7

[JelleZijlstra]

Add 3.6 and 3.7 to Travis and make them pass.

[blueyed]

Currently it fails with a SyntaxError with 0.7.1 (which is very old already):

  File "…/project/.venv/lib/python3.7/site-packages/aiozmq/rpc/base.py", line 251
    fut = asyncio.async(coro, loop=self.loop)
                      ^
SyntaxError: invalid syntax

There have been fixes in this regard on master.
So a new release alone might suffice?!

[JelleZijlstra]

The tests still don't pass on 3.7, and the fixes are somewhat tricky. I've been working on getting it fixed but haven't had the time yet to finish it up. After everything is green on 3.7 I'll do a release.

[petterreinholdtsen]

Is there an alternative to renaming the async() function to another non-reserved name?

[JelleZijlstra]

Yes, we can just use asyncio.ensure_future for that one. There are other problems with 3.7 that are harder to fix, so I didn't get to this yet.

[blueyed]

For reference: #146

[hoefling]

I would like to help with implementing the missing bits for 3.6/3.7 and releasing a new version. What would be the steps for that? Looking at the Travis log, there's only one test that's still failing on 3.7, the ZmqEventLoopTests.test_close_on_error due to changes in python/cpython#4365 (the fd.fileno() in _ensure_fd_no_transport is called on the closed socket, reraising the Socket operation on non-socket).

[JelleZijlstra]

Thanks @hoefling! Yes, that test needs to be fixed—sorry that I let this drop! Once that's done, I can cut a new release with 3.7 support. However, since 3.8 is out now, I'd love to also support 3.8 if it doesn't turn out too much trouble.

[JelleZijlstra]

So in summary, if you are willing to contribute a PR fixing the remaining 3.7 issue, I'd happily review and merge it.

[bastianlb]

@hoefling any progress on this? Am happy to help if you can point me in the right direction.

[logileifs]

seems like this has already been merged, will there be a new release soon with the fix included?