DOC: change example sample spacing

Change the sample spacing in the example so the linear interpolation points line up with the original points
TST: stop shadowing ellip* tests vs boost data
DOC: Interpolation example, Add num=11, 41

and change shape so it still shows the interpolation clearly

[ci skip]
Merge pull request #4242 from endolith/patch-5

DOC: change example sample spacing
Merge pull request #4253 from ev-br/ellip_tst

TST: stop shadowing ellip* tests vs boost data
MAINT: io: Give an informative error when attempting to read a 24 bit wav file.

Also add a note to the docstring of wavfile.read that 24 bit files are not
supported.
MAINT: io: PEP8 clean up in wavfile.py
TST: lib, linalg: fix blas tests with intent(in,out) arguments

f2py intent(in,out) does not guarantee in-place operations.
Merge pull request #4267 from pv/tstf2pyinout

TST: lib, linalg: fix blas tests with intent(in,out) arguments
Merge pull request #4266 from WarrenWeckesser/wav-24bit-error

 MAINT: io: Give an informative error when attempting to read a 24 bit wav file.