Issue #19936: Disable shebang lines in order to prevent using a random
system python.
update pysqlite website (closes #20278)
linkify chain.from_iterable (closes #20272)
Issue #19936: Added executable bits or shebang lines to Python scripts which
requires them.  Disable executable bits and shebang lines in test and
benchmark files in order to prevent using a random system python, and in
source files of modules which don't provide command line interface.  Fixed
shebang line to use python3 executable in the unittestgui script.
Merge heads
Issue #19936: Remove executable bits from C source files and several forgotten
test files.
Issue #20266: Update parts of the Windows FAQ
Fix some typos/grammar in current sections of NEWS.
Added example to recently added cookbook entry.
sort os.listxattr results before comparing it to avoid depending on the
ordering of the directory information in the underlying filesystem.
avoid a compiler warning about assigning const char * to char *.
Issue #20265: Updated some parts of the Using Windows document.

Includes:
-mention cx_Freeze instead of py2exe (at least until py2exe supports Python 3)
-update ActivePython link
-Remove mention of platforms that were never supported by Python 3 (Win9x, DOS)
describe type of Popen streams (closes #17814)

Patch more or less by Nikolaus Rath.
link to builtin open not io.open
rm extra whitespace
Issue #20245: The open functions in the tarfile module now correctly handle empty mode.
Issue #20238: TarFile opened with external fileobj and "w:gz" mode didn't
write complete output on close.
Issue #20243: TarFile no longer raise ReadError when opened in write mode.
Issue #20244: Fixed possible file leaks when unexpected error raised in
tarfile open functions.
Issue #20270: urllib.urlparse now supports empty ports.