Heavy sleeper/doc

Random number (3d15) is added to effective distance of all sounds when you're asleep. That gives a ~92% chance of not hearing a zombie banging on a window directly next to you and more than 50% chance of not hearing 7 consecutive of such "window bangs". It is not powerful enough to let you sleep through a noisy bionic acting up.

Adds 2 to the threshold of pain required to wake up.