bpo-31781: Prevent crashes when calling methods of an uninitialized zipimport.zipimporter object (GH-3986)

and in codecs.escape_decode() when decode an escaped non-ascii byte.

* bpo-31819: Add AbstractEventLoop.sock_recv_into()

* Add NEWS

* Add doc

This used to be the case on Python 2.  Commit
212b590e changed the implementation for Python
3, making the `log()` method of LogAdapter call `logger._log()` directly.  This
makes nested log adapters not execute their ``process()`` method.  This patch
fixes the issue.

Also, now proxying `name`, too, to make `repr()` work with nested log adapters.

New tests added.

Due to a bug in the initial fix, the setter was in fact creating a different
property.  This is now fixed.

The word "difference" from missing the sentence.
This clarifies that it compares the difference between the two objects.

Fix timeout rounding in time.sleep(), threading.Lock.acquire() and
socket.socket.settimeout() to round correctly negative timeouts between -1.0 and
0.0. The functions now block waiting for events as expected. Previously, the
call was incorrectly non-blocking.

Even if one selects a font that defines a limited subset of the unicode
Basic Multilingual Plane, tcl/tk will use other fonts that define a
character. The expanded example give users of non-Latin characters
a better idea of what they might see in the IDLE shell and editors.

To make room for the expanded sample, frames on the Font tab are
re-arranged. The Font/Tabs help explains a bit about the additions.

bpo-31803: time.clock() and time.get_clock_info('clock') now emit a
DeprecationWarning warning.

Replace time.clock() with time.perf_counter() in tests and demos.

Remove also hasattr(time, 'monotonic') in test_time since time.monotonic()
is now always available since Python 3.5.

bpo-31799: Make module.__spec__ more discoverable

Always pass -1, or INFTIM where defined, to the poll() system call when
a negative timeout is passed to the poll.poll([timeout]) method in the
select module. Various OSes throw an error with arbitrary negative
values.

bpo-31786: Make functions in the select module blocking when timeout is a small negative value. (#4003)

The new method allows the developer to control when to stop the
feature of mocks that automagically creates new mocks when accessing
an attribute that was not declared before
Signed-off-by: Mario Corchero <mariocj89@gmail.com>

Freeze all the objects tracked by gc - move them to a permanent generation
and ignore all the future collections. This can be used before a POSIX
fork() call to make the gc copy-on-write friendly or to speed up collection.

* Rewrite win_perf_counter() to only use integers internally.
* Add _PyTime_MulDiv() which compute "ticks * mul / div"
  in two parts (int part and remaining) to prevent integer overflow.
* Clock frequency is checked at initialization for integer overflow.
* Enhance also pymonotonic() to reduce the precision loss on macOS
  (mach_absolute_time() clock).

Patch by Pablo.

Follow-up to Victor's patch that enabled autotest to run in IDLE's Shell.

This sentence is removed while backporting to 3.6 branch.
See https://github.com/python/cpython/pull/3982#discussion_r144555768

The _PyTime API handles detects overflow and is well tested.

Document that the signal will only be sent once if internal is equal
to zero.

test_load_source() now replaces the current __name__ module with a
temporary module to prevent side effects.