changed the constructor for a Watcher. Before, you had to explictly pass the name of the watcher as an argument. But most of the time this was the name of the class itself. So the watcher now determines internally its name. The method 'getBasicKey' can be overridden. Also updated some encapsulation

Mage/src/main/java/mage/abilities/keyword/ExertAbility.java

@@ -145,7 +145,7 @@ class ExertedThisTurnWatcher extends Watcher {
     private final Set<MageObjectReference> exertedThisTurnCreatures;
 
     public ExertedThisTurnWatcher() {
-        super(ExertedThisTurnWatcher.class.getSimpleName(), WatcherScope.GAME);
+        super(WatcherScope.GAME);
         exertedThisTurnCreatures = new HashSet<>();
     }