Issue #13597: Fix the documentation of the "-u" command-line option, and wording of "What's new in Python 3.0" about standard streams.

Also fixes issue #13581: `help(type)` wouldn't display anything.

support multiprocessing.Event.

Patch by Philipp Hagemeister.

failing.

traceback if Python is optimized.

 * delay the lookup of the size_t type, it is not available at startup
 * The second argument of the PyFrameObjectPtr constructor is optional, as
   done in other constructors
 * iter_builtins() and iter_globals() methods of PyFrameObjectPtr returns
   an empty tuple instead of None if Python is optimized
 * Fix py-bt and py-bt-full to handle correctly "optimized" frames
 * Frame.get_pyop() tries to get the frame pointer from PyEval_EvalCodeEx()
   if the pointer is optimized out in PyEval_EvalFrameEx()

race condition).

Closes issue 11813.

Patch by Cédric Krier.

wchar*, Py_UNICODE* and bytes may contain embedded null characters/bytes.

Patch written by Arnaud Calmettes.

condition variables to avoid deadlocks in child processes.

redirection or an error.

Patch written by Arnaud Calmettes.

Patch written by Brice Berna.

Patch written by Jérémy Anger.

cannot be decoded

Original patch by Hallvard B Furuseth.

effect of appearing to resolve the issue.  Thanks to Mark Shannon for
noticing.

files, display a message popup and continue rather than crash.
(original patch by Roger Serwy)

Initial patch by sbt.