DOC: spatial/qhull: fix some documentation issues
ENH: spatial/qhull: allow obtaining the vertices of the convex hull

This is most useful for 2-D, where qhull computes a counterclockwise
ordering, which otherwise requires some clunky postprocessing.
add a still-failing test to this failed branch
add a commit to make git not complain when I switch branches
TST: special/mpmath: the digamma failure was just too low dps
BUG: special: add an asymptotic expansion to zeta

This avoids underflows in zeta(s, a) for large a and not too large s
BUG: special: fix loss of precision and wrong branch in expi()
BUG: special: improve complex-valued exp1 accuracy

Use a more sensible method for continued fraction evaluation,
and adjust the region in which the power series is used.

The accuracy is around 1e-12.
Fix typo in scipy.optimize.newton argument validation

A copy-paste error in #2462 broke `scipy.optimize.newton`. The other
zero-finding functions have an `xtol` keyword argument, whereas `newton`
does not; it has just `tol`.
BUG: fix truncnorm numerical issues for non-extreme right tails
BUG: use np.* instead of math.* to avoid problems with complex numbers
MAINT: add expm_multiply to scipy.linalg
MAINT: remove the expm_multiply from linalg because I am too noob at python to figure out the cyclic import issues
TST: add complex test
ENH: More helpful error reading bad mat4 file

Prompted by discussion here:

https://github.com/scipy/scipy/issues/2452

Tell user what matrix they are reading and how they might get to useful
data nevertheless.
BF: allow any sequence for variable_names and mat4

Mat4 `variable_names` parameter that was not a list raised an error;
cast iterable to list to allow tuples etc as input.
BUG: gh-2496
TST: truncnorm test with a>0
RF: remove circular reference in interp1d

interp1d was keeping references to self via a reference to one of its
methods, preventing it being cleared from memory without garbage
collection.
NF: garbage collection utilities

Context managers for looking at garbage collection