added mealplan, shopping list, filemanager and app

UML/TastyPages_Use-case.drawio

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

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

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

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

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