Keep Inventory Cost

I'd like to suggest that the keepInventory gamerule be changed to an integer, where it costs an amount of experience levels to keep your inventory. Default is -1, of course, meaning keepInventory is disabled. 0 for free respawn. Any number above that? If the player has a minimum of that amount of XP levels, they will keep their inventory contents and the specified cost will be reduced from their levels. Otherwise, they will follow keepInventory = false behavior. For example, if the cost is set to 10 levels, and the player has 32 levels when they die, they respawn just the way they were, except with 22 levels left.

This would help multiplayer survival servers by a mile, while allowing normal players to play with the original gamerule. It would allow SMPs to use gamerule while preventing the players from being a one-man-army against, say, the ender dragon. It allows for more forgiving gameplay without destroying the balance of risk and reward.