Rather than representing them as "-9223372036854775808",
we now represent them as "'NaT'", as in datetime64 arrays.
Note this changes the numpy.core.arrayprint printer, not the builtin
printer.

Deprecated, removed from numpy/core/arrayprint.py.

This is to make it easier to find and remove deprecated features.
It would be a good idea if all deprecations were made with similar
comments.

Closes gh-5684.

[ci skip]

In PR #5358, np.diagonal was modified to return whatever array type it took in.
Also, np.cumsum and np.clip return the same array type. So, np.ravel's behavior is surprising.
Two tests which were expecting np.ravel to return an array have been changed.
Also, the optional `order` parameter was added to MaskedArray.ravel to make it compatible
(matrix.ravel already had this parameter).

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