Minor update: v0.6B, some UI improvements — Polymino Steam update #681651

When multiple players connect on the same frame, the game will warn about the possibility of duplicate controllers, and guide the players to the controller list menu where this can be checked and corrected. When Player 1 tries to start the game but can't, the button or text corresponding to the reason why will flash. For example, if the game can't start because a player's control binds aren't valid, their "Rebind Controls" button will flash. The game now automatically deletes old log files, so players don't have to worry about the amount of disk space adding up.