MAINT: Unused import
PY3: dealing with izip
MAINT: remove unused import
PY3: int vs long
PY3: another izip instance
PY3: map/list
PY3: map/list + assertItemsEqual renamed to assertCountEqual in py3, so
used assertListEqual instead
PY3/BUG: Function was closing a file it didn't open
PY3: a bit more zip/range work
PY3: division
PY3: no basestring in py3
PY3: deal with iteritems.

viewitems (py2.7+) has the same behaviour as the .items method in py3
(namely set-like functionality and efficient iteration).
MAINT: fix argument order to (expected, actual)
MAINT: no reason not to use new style classes in py2
MAINT: forgot to remove `.iteritems`...
DEP: Don't use deprecated function
PY3: long/int
PY3: StringIO
PY3: Input to md5 must be bytes

This changes do not affect behaviour in Py2.
PY3: Use next function, never next method.