fixed some getter methods -> got rid of writable references. better error messages. fixed bug in recipe manager where recipes were created in a wrong way (put name as key instead of code)

This reverts commit 2b0b34d1

moved HeaderController into new package. Now displaying NutritionTable in MealPlan. -> going to turn it into a component to reuse it in RecipeView. Introduced parallel search to RecipeSearch.

moved HeaderController into new package. Now displaying NutritionTable in MealPlan. -> going to turn it into a component to reuse it in RecipeView. Introduced parallel search to RecipeSearch.

rounded category boxes, redesigned add recipe buttons in mealplan, display categories in recipeview, improved GUI

added header to ingredient-creator; in the shopping list flipStatus works and checkboxes are still checked after switching pages

added app icon, added "back" button to recipe creator. now creating recipes and adding them to the recipe manager