Makes the top sprite visible on liquid turret icons (#4683)

* Add top region to liquid turret icons

* Attempt to change outline icon generation

* Draw regions above the outlined icon over it

* Draw regions **above** the outlined icon over it

* Add clarrifying comment

* Implement backwards compatibility for mods

* an -> any

core/src/mindustry/world/blocks/defense/turrets/LiquidTurret.java

@@ -27,6 +27,7 @@ public class LiquidTurret extends Turret{
         hasLiquids = true;
         loopSound = Sounds.spray;
         shootSound = Sounds.none;
+        outlinedIcon = 1;
     }
 
     /** Initializes accepted ammo map. Format: [liquid1, bullet1, liquid2, bullet2...] */
@@ -63,6 +64,12 @@ public class LiquidTurret extends Turret{
         super.init();
     }
 
+    @Override
+    public TextureRegion[] icons(){
+        if(topRegion.found()) return new TextureRegion[]{baseRegion, region, topRegion};
+        return super.icons();
+    }
+
     public class LiquidTurretBuild extends TurretBuild{
         @Override
         public void draw(){