Patch by Chris Jerdonek.

This is analogous to the link for `flie objects` in the description of
'open' that exists in the 2.7 docs, and adds a similar link to the
io docs.

Patch by Chris Jerdonek.

Update the getpeercert() example with a real-world cert showing non-trivial issuer, subject and subjectAltName.

When adding a message from a binary file, \r\n was translated to
\r\r\n in the message body.

Patch by Serhiy Storchaka.

Patch by Chris Jerdonek.

Patch by Chris Jerdonek.

Patch by Chris Jerdonek.

Patch by Yury Selivanov.

on Windows without the "if __name__ == '__main__'" idiom.

Fix #15496. Add directory removal helpers to make Windows tests more reliable. Patch by Jeremy Kloth

Patch by Chris Jerdonek.

Patch by Chris Jerdonek.

Thanks to Chris Jerdonek

Daniel Ellis.

Patch by Serhiy Storchaka.

Closes #15620: check for presence of readline.clear_history(), which is apparently missing on some readline versions, before calling it in the test.