For hostile mobs, Fear causes them to flee from their target (like how Creepers flee from Cats).
For players and passive mobs, Fear desaturates and darkens the screen, and makes them more visible to mobs. Mobs will now detect the player from twice as far away, and can see the player through walls.
Ender Dragons, Withers, Wardens, Elder Guardians, and all non-path-aware mobs are immune to fear.
When a player is given Fear for the first time, they are now granted "The Mind Killer" advancement.
Added a new potion: Paranoia, which grants Fear and Darkness
The Potion of Paranoia is currently brewed from adding a Wither Rose to an Awkward Potion. This is a placeholder and will be changed in a later PR.
The Potion of Paranoia can get extended duration by adding Redstone, but cannot be amplified.
Resolves #72