Improve RR Battle management.

Not old battles on old pairings. But rather battles on low number of battles for a pairing. Even if a robot has hundreds of thousands of battles. Those battles were selected randomly before, meaning there may be pairings that only have 2 or 3 battles (possibly, I cannot name any, but it is within the realm of possibility). Which is why I stated select those pairings that have low number of battles, regardless of number of battles the given robot has.