Patch by Ryan Kelly, karl, and Nikolaus Rath.

self parameter is implicit. Mention also that communicate() and wait() are
coroutines.

Patch by Andreas Schwab.

We changed a few details of the pip integration over the course
of the Python 3.4 beta and release candidate cycle, but I hadn't
updated the What's New entry appropriately.

The Py2/Py3 split on POSIX and the generally challenges of
dealing with parallel installs means we haven't attained
complete consistency across all environments, but hopefully
this updated text is clearer about the end result.

Relevant to issue #20909.

closes #20931

new redirect of http://www.python.org/ to https://www.python.org.