Lazy loading of results from graph traversal.

    Changed to-list! to: "Collects results lazily, makes efficient use
    of the the lazy nature of pipes/gremlin graph walking."
    
    Note, this causes two tests to fail.  I then added two equivalent
    tests which have been modified slightly and now pass. I believe
    this is really a design decision.  Since the new way of running these 
    tests is a bit awkward,  and could cause bugs...  on the other hand
    there are many benefits from lazy loading of results,  and it is really
    much more idiomatic for Gremlin.
    
    See test/ogre/branch/if_then_else_test.clj and the function
    show-the-problem-above for some "discussion" of this issue.