BUG: ensure raising of invalid on bad complex powers

put inf - inf into a volatile variable so it is not optimized away by
compilers.
BUG: fix bad alignment asserts

if the arrays are smaller than a vector they don't need to be aligned.
Merge pull request #3726 from juliantaylor/dbg-fixes

Dbg fixes
MAINT: Make the qr raw mode test independent of the LAPACK library.

The qr factorization is not unique and the values returned by the raw
mode may differ between LAPACK versions. Consequently, the results
cannot be checked against known values.

Closes #3703.
BUG: f2py, fix decref on wrong object

missing brackets causes decref on an wrong object.
shows itself as abort with negative refcount in test_callback using
python-dbg.
Merge pull request #3728 from juliantaylor/f2py-negative-refcount

BUG: f2py, fix decref on wrong object
Merge pull request #3723 from charris/workaround-dgeqrf-bug

MAINT: Make the qr raw mode test independent of the LAPACK library.
BUG: fix zero initialization with subarray dtypes

closes #3724
Merge pull request #3725 from juliantaylor/fix-subarray-zeros

BUG: fix zero initialization with subarray dtypes
DOC: Make savez_compressed show up in the documentation.

Closes #3708.
Merge pull request #3736 from charris/add-savez_compressed-to-docs

DOC: Make savez_compressed show up in the documentation.