BUG: Fix typo in hermite_e.py.

The hermepow function was incorrectly listed in __all__ as hermpow.
STY: PEP8 fixes for files in numpy/polynomial.

The rather lax standards used in scipy were used to identify the
needed style fixups.
MAINT: Remove unused variables and imports in numpy/polynomial/*.py.

Detected by pyflakes.
STY: PEP8 fixes for numpy/polynomial/tests/*.py.

Made conformant with the standards of scipy.
MAINT: Fix blemishes in numpy/polynomial/tests revealed by pyflakes.
DOC: matrix flatten docstring
DOC: use m for matrix instead of a for array
DOC: clarify matrix flatten docstring
DOC: add minimal clarification to the matrix.ravel docstring
MAINT: fix the import
MAINT: restore optional ravel order and add tests and more docstring lines
DOC: clarify that matrix.ravel only copies if necessary; this is already tested
Merge pull request #4931 from argriffing/matrix-docstrings

DOC: matrix flatten docstring
DOC: Fix typo in _iotools.py docstring.

The error is in the StringConverter.upgrade docstring.
DOC: matrix.squeeze docstring
Merge pull request #4943 from argriffing/matrix-squeeze-docs

DOC: matrix.squeeze docstring
MAINT: small change to squeeze error message
MAINT: use N.ndarray instead of core.multiarray.ndarray
Merge pull request #4946 from argriffing/squeeze-bad-axis-size

MAINT: small change to squeeze error message
Merge pull request #4932 from argriffing/ravel-docstrings

DOC: clarify matrix.ravel docstring and add tests