ENH: allow sparse __rmul__ to work with custom types
BUG: special: fix asymptotic expansion in rgamma
BUG: special: fix several issues in poch

Handle better the cases where the gamma functions in the definition hit
poles or over/underflow.

Fixes gh-1437
GEN: special: regenerate files
DOC: enhanced fftpack tutorial
DOC: further changes in fftpack tutorial
enhanced one example
Fixed issue #2720 in tutorial
DOC: remove an obsolete file
adressed review comments, used [] throughout the document
DOC: Add Notes section to chebwin docstring
ENH integrate: quadrature accepts non-tuple args argument

Copy quad behavior accepting a single element (integer) instead of the
expected tuple

Closes gh-2044
BUG: fix the 'lower' attribute of dpotri to make dpotrf/dpotri consistent.
Should close gh-2691

Also remove (deprecated) clapack dpotri/dpotrf functions.
Fix issues/2331: Bode plot returns continuous phase
BUG: issues/2331, change to assert_almost_equal and style improvement
ensure analyticity of associate Legendre function of first kind
changing the doc strings of measurements.sum
correcting the measurements.sum() doc strings
BUG: stats: When handling the arguments to beta_gen.fit, don't rely on np.log
to generate a warning when its argument is less than or equal to 0.
Fixes gh-2771.
BUG: stats: Raise a ValueError in beta_gen.fit if all the parameters are fixed.