Fix fight.speed not getting registered properly.

Should use addCheck in order to have the stored MCAccess instance reset
properly on reloading. Little relevance with this check.

NCPPlugin/src/main/java/fr/neatmonster/nocheatplus/checks/fight/FightListener.java

@@ -69,7 +69,7 @@ public class FightListener extends CheckListener {
     private final SelfHit     selfHit     = addCheck(new SelfHit());
 
     /** The speed check. */
-    private final Speed       speed       = new Speed();
+    private final Speed       speed       = addCheck(new Speed());
 
     public FightListener(){
     	super(CheckType.FIGHT);