MAINT: move npy_is_aligned to common.h

also make it and some other alignment operators a bit faster by using
unsigned integers and bitwise and if possible.
Make use of npy_is_aligned in _IsAligned too.
ENH: add NPY_LIKELY and NPY_UNLIKELY macros for branching hints

Use it for npy_is_aligned expecting alignments of the power of two.
Cuts down the time spent in _IsAligned by the testsuite relative
to the rest of multiarray.so from 0.6% to 0.4%
BUG: Fix PyType_FastSubclass() check for numpy.int_

Signed-off-by: Yury V. Zaytsev <yury@shurup.com>
BUG: Document that numpy.int_ doesn't inherit from int on Py3k

Signed-off-by: Yury V. Zaytsev <yury@shurup.com>
TST: Add regression test to check numpy.int_ inheritance on Py2/Py3

Signed-off-by: Yury V. Zaytsev <yury@shurup.com>
BUG: Fix test_operand_flags test.

The test tests an inner loop in operand_flag_tests.c.src that expects
a long type, but it is tested using 'i8'. This fails when long is not
'i8'.

Closes #3363.
Merge pull request #3526 from zyv/fix_int_inheritance

BUG: Fix PyType_FastSubclass() check for numpy.int_ and Py3k inheritance
Merge pull request #3594 from juliantaylor/is_aligned_maint

MAINT: move npy_is_aligned to common.h
DOC: update example of histogram2d to doctest format.
DOC: fix some minor issues with histogram2d docstring formatting.
Merge branch 'pr/3591' into master.

See https://github.com/numpy/numpy/pull/3591
Merge pull request #3599 from charris/fix-operand-flags-test

BUG: Fix test_operand_flags test.