ENH sparse:  Add support for sparse matrix .min and .max axis arguments.
TST sparse: Tests for sparse matirx min and max axis args.
DOC: additional notes about FFTs, typo fixes, etc.
MAINT: Use boolean defaults for boolean parameter overwrite_x
MAINT: Use boolean defaults for boolean overwrite_x parameter
DOC: Add simple ifft Returns section
DOC: Add examples for DCT, minor changes to DCT docstrings
DOC: elaborate on rfft and dct efficiencies
scipy.signal.wavelets.cwt doc easyfix from #2748 ticket
MAINT: remove leftover check for Python <= 2.5.  Some cleanups of comments.
Merge pull request #2775 from endolith/patch-3

DOC: fftpack: add more notes about FFTs, real FFTs, fix typos, change boolean defaults to False
Merge pull request #2784 from duskglow/doc-cwt

DOC: scipy.signal.wavelets.cwt argument order fix 

Fixes gh-2748
DOC: enhance interp2d docstring, see #2275
Merge pull request #2783 from rgommers/cleanup

MAINT: remove leftover check for Python <= 2.5.  Some cleanups of comments
DOC: enhance splrep docstring, see #2223
Merge pull request #2785 from andreas-h/interpolate_doc2

DOC: interpolate: enhance interp2d docstring, see #2275
ENH interpolate: remove warnings in pchip

Division by zero occurs only at points excluded in the
following calculations, so warning messages can be removed
safely

Closes gh-2357
Merge pull request #2769 from cowlicks/min-max-axis-args

ENH: sparse: matrix min & max axis arguments.
Merge pull request #2786 from loujine/fix-2357

ENH: interpolate: remove warnings in pchip