What's New in Python 3.4: Security improvements
Issue #19157: Include the broadcast address in the usuable hosts for IPv6
in ipaddress.
whatsnew: summary section tweaks.

Removed an entry made redundant by the new security section,
Moved 'marshal' to the section on features other platforms
will need to support, and mention that 'help' is improved
by the inspect/pydoc changes (#19561 msg213153).
whatsnew: mention that upgrading PIP means it doesn't get unistalled.

#19861 msg213156.
fix typo (closes #20892)
merge 3.3 (closes #20892)
whatsnew: doctest finds tests in extension modules (#3158)

#19861 msg213159
improve algorithms_* documentation
merge 3.3
#20030: doc that TestLoader.discover returns a TestSuite.

Patch by Lita Cho.
Merge #20030: doc that TestLoader.discover returns a TestSuite.
whatsnew: spelling errors.

Corrections from Jim Jewett in #19861.