Setting up packages needed for hacking can now just be ~one step

test_ftplib.py passed this time on appveyor 2.7/64-bit. no idea why since it's been consistently failing before now. no versions appear to have changed.

Mark test__fileobject.py flaky on appveyor due to random failures that are apparently timing related.

Use latin-1 as decoding in unquote for conformance with PEP 3333

test_ftplib.py passed this time on appveyor 2.7/64-bit. no idea why since it's been consistently failing before now. no versions appear to have changed.

Mark test__fileobject.py flaky on appveyor due to random failures that are apparently timing related.

The cert for svn.python.org has changed breaking many test_ssl.py cases.

The upstream resolution is being discussed in
https://bugs.python.org/issue25940, but the interim solution was to
disable the failing tests to avoid blocking releases. I'm applying the
same approach here for a temporary fix.

Optimize CFFI backend to use less memory by taking advantage of the libev 'data' pointer. Also simplifies the callback code.

Use a manually locked pure-Python Semaphore implementation on PyPy

Based on http://fxr.watson.org/fxr/source/sys/_types.h#L52 freebsd also
uses short for st_nlink in struct stat.

Not mentioning in the change notes because I have no way to actually
verify. But it shouldn't hurt.

More tests for various uses of locks in a trace function. Make most of them work or at least not deadlock.

The main stated reason for untraceable locks was a bug in Python 2.5,
fixed in all recent versions, so that shouldn't be a concern.

The semaphore takes some careful lock management to come close to
duplicating the thread-safety inherent in Cython's compiled methods.

'pypy -m timeit -s "import g.l.Semaphore; s=Semaphore()"' 's.acquire();s.releas()':

With Cython compiled semaphore: 5usec
With pure-python sempahore: 0.004usec
With pure-python-but-locked semaphore: 0.178usec
Cython on CPython: 0.141usec

Total test runtime is unchanged.

Use the new ssl module on any python version that natively supports it

Make microbenchmarks run on recent versions; allow choosing alternate pythons for easy comparison (E.g., using .tox/py[py]/bin/python.) [skip ci]

Exclude build products of _corecffi_build.py from the sdist, they can
cause a failure to link if the platforms don't match.

Fix a lurking GC-related crash with stat watchers on PyPy, detected by CPython re-using the memory much faster.