ChunkedIterator for Traversable - Regression Test
ChunkedIterator for Traversable - Fixed
ChunkedIterator valid is a bool of chunk

Just some minor code cleanup. The negation of empty is just not necessary and rather clumsy.
ChunkedIterator tests for boundary cases and and below zero.
ChunkedIterator missing value check

Minor change to implement a size equal or greate zero. Also
enforce integer type to make the behavior more distinct.
Merge pull request #417 from hakre/patch-2

ChunkedIterator for Traversable