Polygonal protection bugfixes

core/src/mindustry/game/EventType.java

@@ -9,6 +9,7 @@ import mindustry.net.*;
 import mindustry.net.Packets.*;
 import mindustry.type.*;
 import mindustry.world.*;
+import mindustry.world.blocks.storage.CoreBlock.*;
 
 public class EventType{
 
@@ -283,6 +284,15 @@ public class EventType{
         }
     }
 
+    /** Called when a core block is placed/removed or its team is changed. */
+    public static class CoreChangeEvent{
+        public CoreBuild core;
+
+        public CoreChangeEvent(CoreBuild core){
+            this.core = core;
+        }
+    }
+
     public static class StateChangeEvent{
         public final State from, to;