Mining Fatigue effect with full beacon

Allow players to select Mining Fatigue III with a full-level beacon, in addition to the other possible choices.

This gives players a new mechanic to protect their builds in vanilla multiplayer, as well as introducing possibilities such as jails, dungeons, or custom boss fights without using adventure mode.

Since the effect is applied to everyone, it shouldn't create an unfair advantage and would add a whole new dynamic to how a player can defend his base as well as how others can still breach it from a distance (TNT cannons, etc).