For a long time now, we've been telling people not to compare scores across
queries, yet we maintain the queryNorm() code as an attempt to do this and the
javadocs even promote it. I'm in the process of researching this some more
(references welcomed), but wanted to hear what people think about it here. I
haven't profiled it just yet, but it seems like a good chunk of wasted
computation to me (loops, divisions and square roots). At a minimum, I think we
might be able to refactor the callback mechanism for it just as we did for the
collectors, such that we push of the actual calculation of the sum of squares
into Similarity, instead of just doing 1/sqrt(sumSqs). That way, when people
want to override queryNorm() to return 1, they are saving more than just the
1/sqrt calculation. I haven't tested it yet, but wanted to find out what others
think.

Thoughts?