ENH: improve stats.nanmedian more by assuming nans are rare

Move nans to end of array instead of creating a new array without them.
This is faster under the reasonable assumption that nans are rare.
ENH: add runtime warning for all nan slice of nanmedian
MAINT: use assert_warns instead of a more complicated mechanism
MAINT: copypaste assert_warns from a newer numpy into scipy
MAINT: move a numpy compatibility function into its own file
MAINT: python 3 compatibility boilerplate
ENH: change to use array view in signal/_peak_finding.py
BUG: tools: Fix list of FMA instructions in detect_cpu_extensions_wine.py
DOC: stats: Add 'entropy' to the stats package-level documentation.
Merge pull request #3420 from WarrenWeckesser/doc-stats-entropy

DOC: stats: Add 'entropy' to the stats package-level documentation.
Merge pull request #3419 from WarrenWeckesser/fix-fma-instructions

BUG: tools: Fix list of FMA instructions in detect_cpu_extensions_wine.py
Added 'eps' in optimize.show_options for L-BFGS-B

In scipy.optimize.minimize, when algorithm is L-BFGS-B, there is an
option called eps. However, this options is missing if we use
scipy.optimize.show_options('minimize', 'L-BFGS-B') to look up its
options.
Merge pull request #3427 from yw5aj/master

Added 'eps' in scipy.optimize.show_options for L-BFGS-B
MAINT: Add myself to thanks :)

I worked on scipy.sparse a bit last summer for GSoC.
Thanks again @pv!
Merge pull request #3428 from cowlicks/thanks

MAINT: Add myself to thanks :)
MAINT: tweak cython variables declarations to avoid the warning
'Non-trivial type declarators in shared declaration ...' that is
generated by cython 0.20.
MAINT: special: tweak the generated cython variable declarations in _ufuncs.pyx
to avoid the warning 'Non-trivial type declarators in shared declaration ...'
that is generated by cython 0.20.
GEN: special: regenerate _ufuncs.pyx
BUG: Correcting the normalization of chebwin window function
Merge pull request #3433 from ankit-maverick/chebwin

Correcting the normalization of chebwin window function