ENH: enhance meshgrid to generate 3D grids, sparse grids, matrix indexing.
MAINT: clean up docstring and some minor items in meshgrid.  Remove ndgrid.
BUG: meshgrid: raise error on single input.
TST: meshgrid: test expected shapes for Cartesian and matrix indexing.
STY: meshgrid: some minor changes to address review comments.
MAINT: explicitly check for NaNs in allclose(). Closes #1905.

Also clean up the logic behind handling infs.

The removed seterr call becomes unnecessary when explicitly checking for NaNs.
It was introduced only recently in c4c0e985.
DOC: allclose: document better what happens when Infs or NaNs are present.
MAINT: port few missing changes to 1.6.0 release notes from 1.6.x branch.
Fix unicode string length computation in UNICODE_compare and add test.
Use sizeof(npy_ucs4) instead of hardcoded shift, and make test py3k compatible.
DOC: label the current NA implementation as experimental in 1.7.x

This has been extensively discussed on the mailing list.  See #2072.
DOC: label datetime support as experimental. Closes #2072.
STY: Bit of style cleanup.
BUG: ticket #2086, make datetime and timedelta recognize byte order.

The descriptor construction of these types was ignoring the byteorder
character.
BUG: ticket #2063, make unique return consistent index.

Make unique use  mergesort when return_index is true. This quarantees that
the returned indices are of the first occurrence of the unique elements and
makes the behavior better defined and consistent.
BUG: ticket #2073, fix float16 __array_interface__ bug.
TST: Test float16 __array_interface__.
STY: Cleanup test_half.py a bit.

Make imports from numpy.testing explicit.
Make module runnable from command line.
STY: Style fixes to test_multiarray.

Make imports from numpy.testing explicit.
Break some long lines.
STY: Style fixes to numpy/core/tests/test_regression.

Make imports from numpy.testing explicit.
Make test_unique_stable check against specific results.