BUG: gh-2687 make multiarray dot method accept out array and keyword
args.
FIX: use PyObject_CallMethodObjArgs in array_dot

and make added comments in test_multiarray.py helpful.
BUG: PyString_FromString isn't py3 compatible.

Use PyUnicode_FromString instead.
BUG: use the PyUString_FromString macro for Py3 compat instead.
Merge pull request #2988 from ewmoore/methdot2697

BUG: gh-2687 make multiarray dot method accept out array and keyword args