Added test case for EntrySet iterator that catches in case hasNext() and
next() doesn't behave correctly after last item.
Added test for hasNext() and next() on iterator of Map keys and values
when positioned at end of iterator.
Fixed so iterators of HTreeMap keys, values and entries correctly throws
NoSuchElementException when calling next() when iterator have reached
the end.
Merge pull request #67 from konrade/master

Fix for issue #66