--Have produce-score-matrix, highest-scoring-trace-for-sentence, and highest-scoring-sentence-for-trace working.  Also created pretty-hstft and pretty-hssft that produce pretty text output for highest-scoring-trace-for-sentence and highest-scoring-sentence-for-trace, respectively.
--Currently I make the big score matrix in produce-score-matrix, but I don't use it in the highest-scoring-* functions, instead just looking at one sentence or one trace in those functions.  Would it be better to just compute this matrix once (perhaps when I first load toollib-analysis.sc) and then have the highest-scoring-* functions just reference into this matrix?  This seems to be more complex, but it might be more efficient.