ENH: speed up intp multiply overflow check

Avoid expensive division by checking against half size of the result first.
Speeds up PyArray_NewFromDescr by a factor of two according to perf.
Could still be further improved by making use of cpu overflow flags, e.g. via
clangs __builtin_mul_with_overflow or using gccs __int128 type.
ENH: reduce calls to npy_is_aligned in _IsAligned

one can just bitwise_or the memory and all strides and call npy_is_aligned on
that to get the same result.
TST: improve test speed

move slow test_memmap_roundtrip to slow tests
decrease excessively large array size used in np.sin(x) compuation
TestInterp.test_if_len_x_is_small, the code has no special path for this
large size differences.
MAINT: Make useless imports of oldnumeric and numarray safe.

The oldnumeric and numarray packages were removed in numpy 1.9, but
some packages, e.g. scipy, import them even though they are not used.
This defines both to the string 'removed' in numpy/__init__.py, which
avoids an import error.
BUG: core: consider both C and F order buffers as contiguous
Merge pull request #3827 from pv/fix-gh-3796

BUG: core: consider both C and F order buffers as contiguous
STY: pep8 for npyio

Various pep8 fixes for npyio.py
Also reorganized the imports, and removed the unnecessary (I hope)
`_string_like = _is_string_like` statement.
BUG: fix small issues found with cppcheck

uninitialized use in _strided_to_strided_one_to_n_with_finish
wrong error NULL checks in PyArray_MapIterNew and einsum_sub_op_from_str
double free and memleak in umath_linalg.c.src init_@lapack_func@
Merge pull request #3832 from juliantaylor/static-issues

BUG: fix small issues found with cppcheck
Merge pull request #3826 from charris/add-oldnumeric-numarray-to_init

MAINT: Make useless imports of oldnumeric and numarray safe.
MAINT: fix another wrong NULL check

silences cppcheck error, not a bug as the only caller checks the python
error.
Merge pull request #3838 from juliantaylor/null-fix

MAINT: fix another wrong NULL check
DOC: mention new comparison runtime warnings in release notes
DOC: move support for large files to features

its nothing you should need to worry about when porting to 1.8
DOC: update percentile release notes and add np.array improvement
DOC: minor rewording of partition note
BUG: Allos linalg.solve to handle zero equations.

This was previously correct, but the special case was missing
since the gufunc code cannot handle it.
Merge pull request #3841 from juliantaylor/rnotes-master

update 1.9 release notes and sync 1.8 notes with maintenance branch
Merge pull request #3848 from seberg/solve_0k

BUG: Allos linalg.solve to handle zero equations.
BUG: preserve ndarray subclasses in median

closes gh-3846