Previously we calculated amounts (and therefore, differences) based on cards only, which means that user could earn some extra 'points' in our calculation for giving us many trash cards that we miss, and in exchange for that swap cards from some other game that would normally results in non-neutral difference on that game basis, but neutral+ in overall basis (that we operated on).
This would not cause any serious problem, because ASF ensures that trade is fair before calculating actual neutrality, but it could result in accepting a trade that is neutral+ only at first sight, and non-neutral+ when we take a closer look what we're actually swapping.
The logic was enhanced to handle differences on per-game basis now, and taking minimum in account, so all swaps on per-game basis have to be neutral+ now
Time to enforce some common file layout, as general mess started to annoying me. Sorry in advance for people using custom forks and having merge conflicts, this will help everybody in long-run
