Increase the length of the player input buffer even more

This is a direct sequel to !835 (merged), but this time with a (much, much) larger buffer, allowing a player to freeze for up to 30 seconds before affecting other players.

In practice that should mean that the game no longer "pauses" when someone joins, and that players who are laggy or get a timeout should normally not freeze the server (unless of course the server itself is responsible for the lag)

This is based on !950 (merged).