added 'Shell' and 'ShellControl' and editet the two visitors 'Visitor' and 'VoidVisitor'

Projekte/battleship/model/src/main/java/pp/battleship/model/Shell.java

@@ -0,0 +1,31 @@
+package pp.battleship.model;
+
+public class Shell implements Item {
+
+    private IntPoint target;
+
+    public Shell(IntPoint target){
+        this.target=target;
+    }
+
+
+
+
+
+
+
+
+    @Override
+    public <T> T accept(Visitor<T> visitor) {
+        return visitor.visit(this);
+    }
+
+    @Override
+    public void accept(VoidVisitor visitor) {
+        visitor.visit(this);
+    }
+
+    public IntPoint getTarget(){
+        return target;
+    }
+}

Projekte/battleship/model/src/main/java/pp/battleship/model/Visitor.java

@@ -28,4 +28,6 @@ public interface Visitor<T> {
      * @return the result of visiting the Battleship element
      */
     T visit(Battleship ship);
+
+    T visit(Shell shell);
 }

Projekte/battleship/model/src/main/java/pp/battleship/model/VoidVisitor.java

@@ -25,4 +25,6 @@ public interface VoidVisitor {
      * @param ship the Battleship element to visit
      */
     void visit(Battleship ship);
+
+    void visit(Shell shell);
 }