Sort alphabetically as final tiebreaker

[hdelva]

Somewhat surprising, but we cannot sort alphabetically at the moment since all scoring is number-based. We could add string literals explicitly in the IRankedSubject interface, and use this data in the comparison function -- after the numeric scores have been handled. Unfortunately we are scoring subjects, based on a set of quads that subject appears in, so we can have several literals to sort per subject -- so which one is the most important?