Adds bonus of a specific property to unit. whichUnit Unit which should get bonus. bonusType Property type which is used for adding bonus. Possible values are: A_BONUS_TYPE_DAMAGE A_BONUS_TYPE_ARMOR A_BONUS_TYPE_LIFE A_BONUS_TYPE_MANA A_BONUS_TYPE_SIGHT_RANGE A_BONUS_TYPE_MANA_REGENERATION A_BONUS_TYPE_LIFE_REGENERATION amount Bonus amount which should be added. Returns if bonus was added successfully.