Simplify SWCommand.register

SpigotCore_Main/src/de/steamwar/command/SWCommand.java

@@ -48,7 +48,6 @@ public class SWCommand<T extends CommandSender> {
         }
     }
 
-    private SWCommand<T> instance;
     private Argument<?>[] arguments;
     private BiConsumer<T, ArgumentMap> executor;
     private boolean lastArgRepeatable = false;
@@ -56,7 +55,6 @@ public class SWCommand<T extends CommandSender> {
     public SWCommand(BiConsumer<T, ArgumentMap> executor, Argument<?>... arguments) {
         this.executor = executor;
         this.arguments = arguments;
-        this.instance = this;
     }
 
     public SWCommand(BiConsumer<T, ArgumentMap> executor, boolean lastArgRepeatable, Argument<?>... arguments) {