Add pyatomic.h to the VS project (it wasn't referenced).

* Remove _PyThreadState_Current
* Replace GET_TSTATE() with PyThreadState_GET()
* Replace GET_INTERP_STATE() with _PyInterpreterState_GET_UNSAFE()
* Replace direct access to _PyThreadState_Current with
  PyThreadState_GET()
* Replace _PyThreadState_Current with
  _PyRuntime.gilstate.tstate_current
* Rename SET_TSTATE() to _PyThreadState_SET(), name more
  consistent with _PyThreadState_GET()
* Update outdated comments

Convert _Py_Dealloc() macro into a static inline function. Moreover,
it is now also defined as a static inline function if Py_TRACE_REFS
is defined.

Make _PySys_AddXOptionWithError() and _PySys_AddWarnOptionWithError()
functions private again. They are no longer needed to initialize Python:
_PySys_EndInit() is now responsible to add these options instead.

Moreover, PySys_AddWarnOptionUnicode() now clears the exception on
failure if possible.

* bpo-34523, bpo-34403: Fix config_init_fs_encoding(): it now uses
  ASCII if _Py_GetForceASCII() is true.
* Fix a regression of commit b2457efc.
* Fix also a memory leak: get_locale_encoding() already allocates
  memory, no need to duplicate the string.

Use curses.ncurses_version for conditionally skipping a test.

It was overridden by the lineno of the first decorator. Now it is
the lineno of 'def' or 'class'.

Needs backport to 3.7. In 3.6 the description is correct.

Some FreeBSD buildbots fail to run this test as the eof was not being received by the server if the size is not big enough. This behaviour only appears if the client is using TLS1.3.

Fix 'install-sh' file permission: add execution bit ("chmod +x"),
"-rw-rw-r--." becomes "-rwxrwxr-x.".

After commit d0f49d2f, the output of the
test suite is always buffered as the test output needs to be included in
the JUnit file in same cases (as when a test fails). This has the
consequence that printing or using debuggers (like pdb) in the test
suite does not result in a good user experience anymore.

This commit modifies the test suite runner so it only captures the test
output when the JUnit file is requested to fix the regression so prints
and debuggers are usable again.

Convert Py_XINCREF() and Py_XDECREF() macros into static inline
functions.

* Include memo in the documented signature of copy.deepcopy()

The memo argument is mentioned lower on the doc page under writing a
`__deepcopy__` method, but is not included in the documented function signature.
This makes it easy to miss, and can lead to incorrect/buggy implementations of
`__deepcopy__` -- which is exatly what just happpend to me!

Modules imported last are now cleared first at interpreter shutdown.

A newly imported module is moved to the end of sys.modules, behind
modules on which it depends.

"static inline" should be used directly. Forcing the compiler to
inline is not recommended.

* Convert Py_INCREF() and Py_DECREF() macros into static inline
  functions.
* Remove _Py_CHECK_REFCNT() macro: code moved into Py_DECREF().

Topics include opening, title and status bar, .py* extension, and running.

In commit 372d705d a new optimization to the list() type was introduced but it was not added
to the optimization section in What's new for Python 3.8.

unittest.mock now includes mock calls in exception messages if
assert_not_called, assert_called_once, or assert_called_once_with
fails.

Add a paragraph in "Help and preferences", "Help sources" subsection.

The list() constructor isn't taking full advantage of known input
lengths or length hints. This commit makes the constructor
pre-size and not over-allocate when the input size is known (the
input collection implements __len__). One on the main advantages is
that this provides 12% difference in memory savings due to the difference
between overallocating and allocating exactly the input size.

For efficiency purposes and to avoid a performance regression for small
generators and collections, the size of the input object is calculated using
__len__ and not __length_hint__, as the later is considerably slower.

* Fix potential division by zero in BZ2_Malloc()
* Avoid division by zero in PyLzma_Malloc()
* Avoid division by zero and integer overflow in PyZlib_Malloc()

Reported by Svace static analyzer.

https://bugs.python.org/issue35089

Configuring python with ./configure --with-pydebug CFLAGS="-D COUNT_ALLOCS -O0"
makes "make smelly" fail as some symbols were being exported without the "Py_" or
"_Py" prefixes.

Some projects (e.g. Chameleon) create ast.Str containing an instance
of the str subclass.

Fix a bug I introduced in #9864 by which coroutines are treated as synonymous of function coroutines.

Also, fix the same mistake (coroutines == function coroutines) already present in other parts of the reference.

I'm very sorry for the hassle.

We now use git and backporting instead of hg and forward merging.

There is only one trivial change to idle.rst. Nearly all the changes to help.html are the elimination of chapter and section numbers on headers due to changes in the build system. help.py no longer requires header numbering.