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.

Categories, recipes and ingredients now saved in hashmap together with their associated code and a whole bunch of refactoring to go along with it. TypeAdapters for Recipes, NutritionTables and Categories. Saving and retrieving Recipe, NutritionTable and Category to / from JSON works (see tests).

abstract class BaseController, figuring out dependency injection into JavaFX controllers, added enum View.java to get correct Scene object (with correct constructor)

added BaseController that stores FXML files for all views, started bugfixing for equals methods, started working on recipe view fxml file