attackthrottle {rate} {time}
rate: chance to cancel attack (must be between 0.0 and 1.0)
time: in seconds, how long should this entity stay tame until next check, the engine will generate a random number between 0 and this value.
note: some action will cancel the timer, for example, getting hit. Seeing the target block or attacking will also affects the timer. A value of 0.5-0.75 should be OK.
2. Move AI character grab logic from move code to attack code.
3. Only check attack every 4 loops. Assume it won't cause much difference because even 0.04 second is beyond human reaction. This should be able to save some CPU power.
