register default deprecation warning filter....
register default deprecation warning filter.
warn user if (s)he use a deprecated feature interactively.
Closes
#8478
In [1]: %run -i foo
In [2]: foo()
foo.py:4: DeprecationWarning: using a non-integer number instead of an
integer will result in an error in the future
print('x'*np.float64(3.5))
xxx
In [3]: from foo import foo
In [4]: foo()
xxx
