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.

Now that Python < 2.6 is no longer supported we can use the errstate
context manager in places where constructs like
```
    old = seterr(invalid='ignore')
    try:
        blah
    finally:
       seterr(**old)
```
were used.

Rename sys.maxint to sys.maxsize when the Python version is >= 3.  This
change was made in Python 3 because all integers are 'long' integers and
their maximum value bears no relationship to the C type that int used to
represent. The new sys.maxsize value is the maximum value of Py_ssize_t.
This change has not led to any reported problems since the numpy 1.5
release.

Closes #3082

MAINT: Cleanup some imports involving reduce.

Add `print_function` to all `from __future__ import ...` statements
and use the python3 print function syntax everywhere.

Closes #3078.

Because reduce has been available in functools since Python 2.6 we
can get rid of the version checks we currently have before we import
it.

Also removes some reduce related skips in tools/py3tool.py. We were
already skipping the reduce fixer so this has no effect other than
cleaning up the code.

DOC: Formatting fixes using regex

The new import `absolute_import` is added the `from __future__ import`
statement and The 2to3 `import` fixer is run to make the imports
compatible. There are several things that need to be dealt with to make
this work.

1) Files meant to be run as scripts run in a different environment than
files imported as part of a package, and so changes to those files need
to be skipped. The affected script files are:

    * all setup.py files
    * numpy/core/code_generators/generate_umath.py
    * numpy/core/code_generators/generate_numpy_api.py
    * numpy/core/code_generators/generate_ufunc_api.py

2) Some imported modules are not available as they are created during
the build process and consequently 2to3 is unable to handle them
correctly. Files that import those modules need a bit of extra work.
The affected files are:

    * core/__init__.py,
    * core/numeric.py,
    * core/_internal.py,
    * core/arrayprint.py,
    * core/fromnumeric.py,
    * numpy/__init__.py,
    * lib/npyio.py,
    * lib/function_base.py,
    * fft/fftpack.py,
    * random/__init__.py

Closes #3172

In python3 range is an iterator and `xrange` has been removed. This has
two consequence for code:

    1) Where a list is needed `list(range(...))` must be used.
    2) `xrange` must be replaced by `range`

Both of these changes also work in python2 and this patch makes both.

There are three places fixed that do not need it, but I left them in
so that the result would be `xrange` clean.

Closes #3092