createBullets(quantity, key, frame, group) → {Phaser.Weapon}
This method performs two actions: First it will check to see if the Weapon.bullets Group exists or not,and if not it creates it, adding it the group given as the 4th argument. Then it will seed the bullet pool with the quantity number of Bullets, using the texture key and frameprovided (if any). If for example you set the quantity to be 10, then this Weapon will only ever be able to have 10 bulletsin-flight simultaneously. If you tr