New random number policy & body part health nerf

Randomness

old power/skill randomness: 

1. draw a random number R from normal distribution of mean = power/skill base value and std deviation = 0.5
2. return max(0, R)

new randomness:

1. draw a random number R from normal distribution of mean = power/skill base value and std deviation = mean * 0.4
2. if R > mean then R = 2 * mean - R
3. return max(0, R)

Body part health nerf

every sub-part of body parts are now has lower healthes than base health value