Also add some more tests. Based on patch by Sye van der Veen.

Most of the docs has already been updated in c3c188a0325a.

Patch by Raphael Das Gupta.

Augment htest to include all major IOBinding functions.

Issue #26217: resize_compact() must set wstr_length to 0 after freeing the wstr
string. Otherwise, an assertion fails in _PyUnicode_CheckConsistency().

Issue #25907: Use {% trans %} tags in HTML templates to ease the translation of
the documentation. The tag comes from Jinja templating system, used by Sphinx.

Patch written by Julien Palard.

Issue #25843: When compiling code, don't merge constants if they are equal but
have a different types. For example, "f1, f2 = lambda: 1, lambda: 1.0" is now
correctly compiled to two different functions: f1() returns 1 (int) and f2()
returns 1.0 (int), even if 1 and 1.0 are equal.

Add a new _PyCode_ConstantKey() private function.

A single call to Pool.apply_async() will create only one process. To use all
of the pool's processes, it should be invoked multiple times:

    with Pool(processes=4) as pool:
        results = [pool.apply_async(func, ()) for i in range(4)]

Patch by Davin Potts.

PyMapping_Values in Include/abstract.h and Doc/c-api/mapping.rst.

Patch contributed by Sonali Gupta.

This change helps to ignore text of PSF, BEOPEN.com and CNRI licenses when
translating the documentation. Patch written by Julien Palard who is
translating Python 3.5 doc to french. Text of other licenses already used
preformatted format.

Issue #24520: On FreeBSD, fpgetmask() was deprecated long time ago.
fedisableexcept() is now preferred.

Issue #26154: Add a new private _PyThreadState_UncheckedGet() function which
gets the current thread state, but don't call Py_FatalError() if it is NULL.

Python 3.5.1 removed the _PyThreadState_Current symbol from the Python C API to
no more expose complex and private atomic types. Atomic types depends on the
compiler or can even depend on compiler options. The new function
_PyThreadState_UncheckedGet() allows to get the variable value without having
to care of the exact implementation of atomic types.

Changes:

* Replace direct usage of the _PyThreadState_Current variable with a call to
  _PyThreadState_UncheckedGet().
* In pystate.c, replace direct usage of the _PyThreadState_Current variable
  with the PyThreadState_GET() macro for readability.
* Document also PyThreadState_Get() in pystate.h

non-UTF-8 encoding.

A machine can have more than one IP addresses so
socket.gethostbyname(socket.gethostname()) probably won't return the correct
one.

Initial patch by Carlo Beccarini.

Issue #11816: Fix bytecode_helper to handle correctly errors. Don't use
unassigned variables.

Debugging by Eryk Sun.

Patch contributed by Ryder Lewis.

The previous test relied on a remote server, which currently seems to be
shutting the connection down once TLS has been set up, causing an EOFError.
Now the test is implemented using a minimal NNTP server running in a
background thread.