Use traditional (win-based) Elo instead of score-based.

Use traditional (win-based) Elo instead of score-based.

Using traditional Elo instead of score-based Elo eliminates a lot of
confusion and drama surrounding losing points when winning and
gaining points when losing. I think this is a better reflection of
what we're after - the highest ranking players have won the most.
This has an intended side-effect of encouraging ALL players to
play more, because even pros have no penalties by playing newer
players.