template <typename... ContainerTraits>
class TestObj
Container test objects are objects which...
1) Store a size_t value
2) Store a 'visited' flag for use when testing iterators
3) Derive from TestObjBase (so that live object counts are maintained)
4) Exercise the base class helper for the container which makes an object
containable (SinglyLinkedListable for SinglyLinkedList, etc...)
5) Have storage of the appropriate type to exist in another version of the
container being exercised.