smart battles

Got this working, just dogfooding it a bit myself before posting it since it's a pretty major change. Data files are now (gzipped) XMLs with the raw scores from every battle and everything's recalculated on the fly. (That was actually most of the work.) Comes out to about 100 kb for 3k battles.

It runs 2 seasons vs each bot then does smart battle selection with the formula above to try to increase overall accuracy as quickly as possible. It's nice to see test runs where only 2 battles were run vs HawkOnFire. =) 5% of the time, it instead chooses randomly among the bots with fewest battles, to try to mitigate cases where the variance was randomly low in the initial battles. (I can make this configurable if/when anyone cares.)

It won't schedule two battles vs the same bot unless the number of bots is <= the number of threads. Otherwise, you'd keep scheduling that bot until the battle finishes. I could instead estimate how many times in a row it would still be worth scheduling it, but that seems like a lot of work for a corner case.

I think this is going to save a heck of a lot of CPU time. The XML data files will also make it easier to let you store arbitrary score data in the custom scoring stuff.