MAINT: stats: Add note about change to scoreatpercentile in release 0.12.0.

Also make a test of scoreatpercentile on a 2D array more explicit
about the expected result.

Closes gh-3329.
Fix PEP8 W391 issues (blank line at end of file).
Fix PEP8 E712 issues (comparisons to True).
Misc PEP8 fixes.
MAINT: optimize: remove dead code

ndim of arrays that were previously flattened were being checked.
(The check and flatten could be swapped, but that would change current
behavior.)
ENH: integrate: odeint: Handle exceptions in the callback functions.

Basic idea:  There are C functions that are called by the Fortran solver
LSODA.  These C functions call the user's Python callback function (i.e. the
definitions of the differential equations and Jacobian).  If an error occurs
in the Python code, the C functions set the "number of equations" parameter
to -1 to indicate that an error has occurred.  The Fortran code will now
check for this value, and simply return if it is detected.  The error set
in the user's python code will propagate up to the Python code that called
LSODA, so the user gets the exception.

Change summary:
__odepack.h:
    In the callback functions, instead of calling PyErr_Print() when an
    error occurs, set *n = -1.
multipack.h:
    Don't use PYERR2 (which does PyErr_Print and then sets a new exception).
    Instead, just let the error propagate.
Fortran code:
    Check for neq(1) being -1 on return from calls to user's code.
ENH: optimize: handle NaNs in curve_fit

curve_fit now raises ValueError if input data contains NaNs.
Previously curve_fit would return nonsensical results.
BLD: update Bento build for special.ellip_harm changes.
Merge pull request #4052 from WarrenWeckesser/odeint-exceptions

ENH: integrate: odeint: Handle exceptions in the callback functions.
Merge pull request #4156 from larsmans/optimize-dead-code

MAINT: optimize: remove dead code
BUG: Workaround for SGEMV segfault in Accelerate (OSX version 10.9)

Corrects scipy.linalg.blas.sgemv, ARPACK, SuperLU
similar to: numpy/numpy#5223
ENH: optimize: add check_finite flag to curve_fit
Merge pull request #4186 from pv/pr-4105

BUG: Workaround for SGEMV segfault in Accelerate
Merge pull request #4058 from WarrenWeckesser/maint-scoreatpercentile

DOC: stats: Add note about change to scoreatpercentile in release 0.12.0.
Merge pull request #4187 from ev-br/pr/3923_

ENH: optimize: handle NaNs in curve_fit
REL: set version to 0.16.0-dev
ENH: fitpack2: add check_finite optional argument to *Spline classes

If an input array contains nans, FITPACK silently returns all
spline coefficients as nans. Better bail out early with a
sensible error message.
Merge branch 'pr/3980' into master.

See https://github.com/scipy/scipy/pull/3980
ENH: stats: return namedtuple for describe output
MAINT: some return value name changes and style tweaks to stats.describe.

See gh-3991 for discussion of the name changes.