Make Popen.wait() raise the right exception on PY3 windows so that subprocess.call() doesn't hang if the process doesn't exit within the timeout.

It might be simple to make subprocess more-or-less work under Windows/Py3. First step is to import the moved names from the right place. Fixes #668. Fixes #669.

Maybe we don't need to include the apparently borked header after all? Hate to make changes to libev source though.

Trying latest batch magic from https://github.com/ogrisel/python-appveyor-demo/tree/master, claims 3.5 support

Also, this comes on the heels of adding back __weakref__ to Semaphore.
This becomes a field in the struct and the field is cleared in
tp_dealloc. It seems like this would trigger the memory leak bug when
taking references to a subclass, but testing seems to show that
doesn't happen. I guess PyPy handles that specially:

>>>> objgraph.show_growth()
>>>> _ = [weakref.ref(gevent.thread.LockType()) for i in range(1000)]; del _
>>>> objgraph.show_growth()
>>>>

[skip ci]

Make sure gevent.lock.Semaphore can be weak referenced. This must be explicitly declared in cython. Fixes #666.

bwc for gunicorn in corner case (https://github.com/benoitc/gunicorn/blob/master/gunicorn/workers/ggevent.py#L219) [skip ci]

internal documentation for the numerous attributes used in of WSGIHandler; also eliminates pylint warnings about setting undeclared attributes

DummyThread objects are much lighter weight and don't allocate and then immediately delete a Semaphore.

This matters for servers that handle each request in a new greenlet (e.g., gunicorn) because logging caused these objects to be created. Avoiding the Semaphore is especially important on PyPy.