This reverts commit 7141f40b58ed1e7071cde78ab7bc8ab37e9c5983,
reversing changes made to 8fa6e3bef26a6d4a2c92f2824129aa4409be2590.

The original broke some pandas tests. The current plan to get this
in is

* reversion
* issue FutureWarning in 1.11 and 1.12
* make the change in 1.13.

Now, NaT compares like NaN:
- NaT != NaT -> True
- NaT == NaT (and all other comparisons) -> False

We discussed this on the mailing list back in October:
https://mail.scipy.org/pipermail/numpy-discussion/2015-October/073968.html

This is for backward compatibility. We may want to add more testing
functions if other folks run into problems in the 1.10 release.

Also fix "*" imports.

The formatting of test arrays is not fixed for multiple spaces following
"," and other violations that are common in tests. To be precise, E241
and E201 are added to the errors that are excluded.

Also

* Add __all__ to numpy/ma/testutils.py
* Remove various stray "#"

We might want to consider removing/refactoring both numpy/ma/bench.py
and numpy/ma/timer_comparison.

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

Closes #3078.

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

This should be harmless, as we already are division clean. However,
placement of this import takes some care. In the future a script
can be used to append new features without worry, at least until
such time as it exceeds a single line. Having that ability will
make it easier to deal with absolute imports and printing updates.

assert in non-testing files that should be checked for correctness.