Potion of Blindness

Adds a Potion of Blindess to the game that can be thrown at mobs to significantly reduce their targeting range.  It also tweaks the vanilla blindness effect to make it work on mobs.

Unlike in vanilla, where blindness has no effect on mobs other than the player, mobs hit with this potion will suffer a 1/10x modifier to their sight range which stacks with other visibility modifiers such as skulls or invisibility potions, note that this will not work if they have already seen you.

requires mixin bootstrap until forge ships mixin https://github.com/LXGaming/MixinBootstrap