DEP: put back veccdf/vecfunc/vec_generic_momemt in stats.distributions.

Removed erroneously in gh-3243 for 0.14.0.  These methods were always
private ones but not marked as such, and as the comments on gh-3243 show
they were used. Hence now deprecated.
ENH: cluster: reimplement the update-step of K-means in Cython
MAINT: cluster: remove the conditional import for _vq
BUG: signal: In lfilter_zi, b was not rescaled correctly when a[0] was not 1.
Merge pull request #3770 from WarrenWeckesser/lfilter_zi-bug

BUG: signal: In lfilter_zi, b was not rescaled correctly when a[0] was not 1.
DOC: Fix formatting for Raises section
DOC: Add simple examples, link function names, mention that input arrays are converted to float (no integer or complex or object)
DOC: minor edits to spatial.distance.cdist docstring.
Merge branch 'pr/3746' into master.

Reviewed at https://github.com/scipy/scipy/pull/3746
BUG: signal.filtfilt: make a and b coefficients atleast_1d array

The following crashed before this fix::

    import numpy as np
    from scipy.signal import filtfilt
    x = np.random.randn(100)
    y = filtfilt(np.ones(5)/5, 1, x)
Merge branch 'pr/3701' into master.

Fixes bug in signal.filtfilt.

Reviewed at https://github.com/scipy/scipy/pull/3701
ENH: Implement faster multivariate integration in scipy.integrate.

The numerical integration routines in SciPy use a well-tested, fast, Fortran
library. The computational cost of integration with these routines can be
greatly reduced if the function to be integrated is compiled and passed to
the library directly, avoiding callbacks to the Python interpreter.
TST: Preliminary implementation of unit tests for faster integration.
TST: Cross-platform build and install of unit tests.
DOC: Updated THANKS.txt and scipy 0.15.0 release notes.
DOC: Add Ctypes integration tutorial.
MAINT: fix formatting of ctypes section in integrate tutorial.
MAINT: cluster: some cleanups in vq.pyx
Merge branch 'pr/3262' into master.

Adds support for direct callbacks to C functions via ctypes
for multivariate integration.

Reviewed at https://github.com/scipy/scipy/pull/3262
Merge pull request #3685 from rgommers/stats-veccdf

DEP: put back veccdf/vecfunc/vec_generic_momemt in stats.distributions.