mktemp only returns a filename, a malicous user could replace it before
it gets used.

Compatibility with Python3, which dosn't have string.lowercase.

missing brackets causes decref on an wrong object.
shows itself as abort with negative refcount in test_callback using
python-dbg.

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.

Because Numpy 1.8.0 will no longer supports Python versions < 2.6 we
no longer need to check for that and can also remove the code that is
specific to those earlier versions.

To make this a bit safer, the toplevel setup.py file now contains a
check of the Python version number and raises an error when run by an
unsupported version.

The f2py executable has a shebang which uses the default python, rather
than the python it was compiled for.  This causes issues for deployment
of numpy (+f2py) across systems which have different environments.

This fix uses sys.executable to determine the resulting hardcoded
python to use.

The idioms fixer makes the following replacements.

1) int <- bool
2) comparison or identity of types <- isinstance
3) a.sort() <- sorted(a)

There were two problems that needed to be dealt with after the
application of the fixer. First, the replacement of comparison or
identity of types by isinstance was not always correct.  The isinstance
function returns true for subtypes whereas many of the places where the
fixer made a substitution needed to check for exact type equality.
Second, the sorted function was applied to arrays, but because it treats
them as iterators and constructs a sorted list from the result, that is
the wrong thing to do.

Closes #3062.

Python 3 removes the builtin types from the types module. The types
fixer replaces such references with the builtin types where possible
and also takes care of some special cases:

    types.TypeNone           <- type(None)
    types.NotImplementedType <- type(NotImplemented)
    types.EllipsisType       <- type(Ellipsis)

The only two tricky substitutions are

    types.StringType         <- bytes
    types.LongType           <- int

These are fixed up to support both Python 3 and Python 2 code by
importing the long and bytes types from numpy.compat.

Closes #3240.