hidden skill rating

[Thrutchy]

I think the system should have these changes:
* For each game type, drop players from the published top-200 list after a certain amount inactivity in league play for that game type. This should have no impact on hidden ranking.
* Gradually relax the matchmaking the longer a player waits for a game, but limit the relaxation. A top-10 ST should never be matched with anything less than another ST, I think.
* Don't allow players to game the system as P1. Right now, the highest ranked active player could easily play all P1 games on the maps they are best at with the race they want for each map. I'm not sure what the best solution is, but this should be fixed.