added mealplan, shopping list, filemanager and app

src/main/java/mi/hdm/App.java

+package mi.hdm;
+
+public class App {
+    public static void main(String[] args) {
+        System.out.println("Starting App");
+    }
+
+    public void save() {}
+}

src/main/java/mi/hdm/FileManager.java

+package mi.hdm;
+
+public class FileManager {
+    private static final FileManager fileManager = new FileManager();
+
+    public static FileManager getInstance() {
+        return fileManager;
+    }
+
+    public void serializeToFile(App app) {}
+
+    public App deserializeFromFile(String filepath) { return null; }
+}

src/main/java/mi/hdm/mealPlan/MealPlan.java

+package mi.hdm.mealPlan;
+
+public class MealPlan {
+    private static final MealPlan mealPlan = new MealPlan();
+
+    public static MealPlan getInstance() {
+        return mealPlan;
+    }
+
+    public void addRecipeTomMealPlan(Recipe recipe, int day) {}
+
+    public void clear(int day) {}
+
+    public void clear() {}
+
+    public void get(int day) {}
+}

src/main/java/mi/hdm/mealPlan/NutritionCalculator.java

+package mi.hdm.mealPlan;
+
+public class NutritionCalculator {
+}

src/main/java/mi/hdm/shoppingList/ShoppingList.java

+package mi.hdm.shoppingList;
+
+import java.util.HashMap;
+import java.util.Map;
+
+public class ShoppingList {
+    private final Map<Ingredient, Boolean> list;
+
+    private static final ShoppingList shoppingList = new ShoppingList();
+
+    private ShoppingList() {
+        list = new HashMap<Ingredient, Boolean>();
+    }
+
+    public static ShoppingList getInstance() {
+        return list;
+    }
+
+    public void clear() {}
+
+    public void markDone(int id) {}
+
+    public void markUndone(int id) {}
+
+    public Map<Ingredient, Boolean> getList() {
+        return list;
+    }
+}