ENH: convert the cryptically named scipy.special information theory functions into ufuncs
TST: add negative values to scipy.special information theory function tests
DOC: improve scipy.special information theory ufunc docstrings
MAINT: add .pxd files
MAINT: simplify kl_div
MAINT: combine multiple ufuncs into the same .pxd file
ENH: add huber loss function to the collection of convexity-related ufuncs
PEP8: pacify the pep8 overseer
ENH: add pseudo-huber loss function ufunc
BUG: stats: correct value of powerlaw.logpdf(0, 1) is 0. Closes gh-3986.
BUG: stats: Better handling of x=0 in the 'exponpow' distribution.

exponpow.logpdf(0, 1) now returns 0.0 instead of nan.

When b < 1, exponpow.pdf(0, b) and exponpow.logpdf(0, b) now
return inf instead of nan.

Closes gh-3982.
BUG: stats: gengamma.pdf(0,1,1) now returns 1.0 instead of nan.

Closes gh-3985.
ENH: using python's warnings instead of prints in fitpack.

When fitpack detects a recoverable problem, it will signal it with
a RuntimeWarning instead of printing to stdout. This way the output
can be programatically silenced or made exceptions.
MAINT: optimize: remove a couple unused variables in zeros.c
BUG: Fix C90 compiler warnings in `NI_MinOrMaxFilter1D`

Variable declarations were preceded by code due to a rebase.
Merge pull request #4006 from jaimefrio/c90_warnings

BUG: Fix C90 compiler warnings in `NI_MinOrMaxFilter1D`
MAINT/DOC: Fix spelling of 'decomposition' in several files.
Merge pull request #4007 from WarrenWeckesser/doc-spelling

MAINT/DOC: Fix spelling of 'decomposition' in several files.
Merge pull request #4004 from WarrenWeckesser/maint-zeros-c

MAINT: optimize: remove a couple unused variables in zeros.c
DOC: stats: Maintenance work on the distribution docs in the stats tutorial.

* Added links to implementations in the list of distributions in the tutorial.
* Removed distributions from the .rst files that are not implemented in scipy:
    continuous.rst:
        Doubly Non-central F
        Doubly Non-central t
        Noncentral beta
        Noncentral chi
        Studentized Range
        Symmetric Power
        Wishart
        Student Z
    discrete.rst
        Discete Gaussian
* Fixed spelling of "Saunders" in "Birnbaum-Saunders".
* Removed extraneous blank lines.