Revert back to previous test behavior.  As we're no longer doing a linear walk, we no longer find these types.

New types "WordSimilarityChecker" and "SpellChecker" now use these types to provide
higher level operations that can add more heuristics into the mix (which are
unrelated to the inner operations of EditDistance and BKTree).

Make it clear from teh API if the edit distance code should bail out early or not when it crosses a threshold.'