Added onRegister and onRemove master functions to registries

eco-api/src/main/java/com/willfp/eco/core/registry/Registry.java

@@ -62,6 +62,7 @@ public class Registry<T extends Registrable> implements Iterable<T> {
         registry.put(element.getID(), element);
 
         element.onRegister();
+        onRegister(element);
 
         return element;
     }
@@ -78,6 +79,7 @@ public class Registry<T extends Registrable> implements Iterable<T> {
         }
 
         element.onRemove();
+        onRemove(element);
 
         registry.remove(element.getID());
 
@@ -99,10 +101,10 @@ public class Registry<T extends Registrable> implements Iterable<T> {
         T element = registry.get(id);
 
         if (element != null) {
-            element.onRemove();
+            return remove(element);
         }
 
-        return registry.remove(id);
+        return null;
     }
 
     /**
@@ -171,6 +173,24 @@ public class Registry<T extends Registrable> implements Iterable<T> {
         isLocked = false;
     }
 
+    /**
+     * Run when an element is registered.
+     *
+     * @param element The element.
+     */
+    protected void onRegister(@NotNull final T element) {
+        // Override this method to do something when an element is registered.
+    }
+
+    /**
+     * Run when an element is removed.
+     *
+     * @param element The element.
+     */
+    protected void onRemove(@NotNull final T element) {
+        // Override this method to do something when an element is removed.
+    }
+
     /**
      * Get if the registry is empty.
      *