MAINT: special: Fix whitespace in cephes/pdtr.c
ENH: special: pdtr and pdtrc give the correct limiting value when m=0.
ENH: special: Return 0 for sufficiently small lambda in pdtrik.
ENH: signal: Allow upsweeps of frequency in the 'hyperbolic' chirp.

The restriction that f0 > f1 > 0 has been removed.  The only requirement
is that f0 and f1 are not zero.  Negative frequencies can be given.
(Even f0 and f1 with opposite signs are allowed, but this is not expected
to be a useful case.)  The degenerate case with f0 == f1 is now also
handled.

Two small changes not directly related to the above change:
* Changed "geometric" to "logarithmic" in the argument of the ValueError
  that can be raised when method="logaithmic".
* Added `t = asarray(t)` in the function _chirp_phase, so the 't' argument
  of `chirp` is now `array_like`.

Closes gh-3285.
BUG: sparse: fix issues with 0-size fancy indexing
TST ensure correct operation of has_sorted_indices
FIX use mangled attribute correctly
STY avoid mangled attributes in has_sorted_indices
MAINT: remove numpy.matrix usage from linalg.matfuncs.py code and enable expm of more array_likes
DOC: clarify `limits` parameter in `winsorize` docstring.
STY: PEP8 the `scipy.stats.mstats.winsorize` function.
DOC: add short explanation to `scipy.stats.mstats.winsorize` doctring.
DOC: clarify matrix vs array in mmio docstrings

mmio docstrings and an error message seemed to imply use of np.matrix,
which is not the case.
BUG: fix behavior of write_values() with empty string in scipy.io.netcdf

fixes #1592
Merge pull request #3310 from matthew-brett/clarify-mmio-matrices

DOC: clarify matrix vs array in mmio docstrings
DOC: fix bpoly docstrings
API: remove axis & direction arguments of bpoly.from_derivatives

(They were not implemented anyway.) The idea is to keep the basic
object simple, and delegate complications to subclasses or wrappers.
MAINT: interpolate: move pchip to _monotone.py
MAINT: interpolate: reimplement pchip to use BPoly

The algorithm itself is intact.
STY: remove code duplication, rename pchip.p to pchip.bpoly
API: make pchip.derivative match PPoly.derivative

Previously, pchip.derivative used to return a value of f'(x)
at a fixed `x`. Now this can be achieved with pchip.__call__,
and pchip.derivative() returns a callable object, representing
the derivative. See gh-3267 for discussion.
ENH: add roots() method to the pchip interpolator.