a maximums to regen and degen

[tprk77]

Add the option to cap the amount of regen or degen. For example, configure a totem to apply regen until a player has 3/4 health, or something like that. Or configure a totem to apply degen until the player has only one heart left; that way the totem can damage, but not kill, the player. This should also apply to hunger regen and degen.