MAINT: merge scalarmathmodule into umath module

There is no good reason it needs to be its own module.
Also removes the undocumented pymath alter/restore functions.
DOC note the effect of #1866 in byteorder discussion
Mention transport argsort for inverting the transposition
ENH: added std::complex support to numpy.i

numpy.i now includes ready-made typemaps for std::complex<float>
and std::complex<double> .  Tests were added to testArray using
a newly defined ArrayZ class.
MAINT: change place where NPY_NO_DEPRECATED_API is defined in f2py.

This makes sure to undef at the end, and by putting the define in the
C code it ensures that the error message is understandable.
MAINT: fft: cleanup in fftpack module

* put string constants in const arrays
* use static functions were possible
* removed a stale comment
* more consistent whitespace
DOC: core: np.divide differences between Py2/3

Fixes gh-5278.
DOC: python-as-glue: remove Instant, PyInline

Both projects appear to be dead.
DOC: remove Weave recommendation

Weave is dead. It's not removed from SciPy yet, but it's deprecated and
doesn't work with Python 3.
Merge pull request #5282 from larsmans/c-fixes

MAINT: fft: cleanup in fftpack module
Merge pull request #5283 from larsmans/divide-docs

DOC: core: np.divide differences between Py2/3
DOC: fix documentation build removing single backticks

using them around setup.py build causes a "error: option -b not
recognized" error from sphinx-build.
Replace them with * for italic.
DOC: sync 1.9.1 release notes

[ci skip]
Merge pull request #5288 from larsmans/glue-docs

DOC: Python as glue
Merge pull request #5284 from juliantaylor/doc-fix

DOC: fix documentation build removing single backticks
Merge pull request #5264 from nils-werner/untranspose

Untranspose method
Merge pull request #5281 from rgommers/f2py-deprecated-api

MAINT: change place where NPY_NO_DEPRECATED_API is defined in f2py.
ENH: add BagObj.__dir__ to numpy.lib.npyio

This allows dir(bagobj), and also enables tab-completion on a BagObj,
which can be useful in an interpreter or IPython
TEST: added test of BagObj
Merge pull request #5291 from wackywendell/bagobj

ENH: add BagObj.__dir__ to numpy.lib.npyio