Run the 2to3 ws_comma fixer on *.py files. Some lines are now too long
and will need to be broken at some point. OTOH, some lines were already
too long and need to be broken at some point. Now seems as good a time
as any to do this with open PRs at a minimum.

Now is as good a time as any with open PR's at a low.

Note that the numpydoc sphinx extensions now reside in their own
repository.

Add remarks on changes due in the next release and FutureWarnings.
Add notes on the new functions in the array C-API.
Add notes on the new function in th ufunc C-API.

DOC: Update HOWTO_RELEASE.rst.txt.

The current version is out of date. Supported Python versions have
changed, the buildbot is no longer reachable, some links are dead,
etc.

The recent Python 3 fix adding encoding="utf-8" to the open function
fails on Python 2 because the encoding keyword is not defined. The
solution is to use io.open, which is available for Python 2.6 and 2.7
and is an alias for open when Python >= 3.0. It is reputed to be slow
when running in 2.6, but that should not be a problem.