Multi shotgun fix (#8460)

* Multi-barrel shotgun fix

* multi-recoil support

* @Nullable for everything

core/src/mindustry/entities/pattern/ShootHelix.java

@@ -1,12 +1,13 @@
 package mindustry.entities.pattern;
 
 import arc.math.*;
+import arc.util.*;
 
 public class ShootHelix extends ShootPattern{
     public float scl = 2f, mag = 1.5f, offset = Mathf.PI * 1.25f;
 
     @Override
-    public void shoot(int totalShots, BulletHandler handler){
+    public void shoot(int totalShots, BulletHandler handler, @Nullable Runnable barrelIncrementer){
         for(int i = 0; i < shots; i++){
             for(int sign : Mathf.signs){
                 handler.shoot(0, 0, 0, firstShotDelay + shotDelay * i,