Merge branch 'master' into 'frontend-testing'

# Conflicts:
#   src/main/java/no/ntnu/idatt1002/demo/controller/AddExpenseController.java
#   src/main/java/no/ntnu/idatt1002/demo/controller/AddIncomeController.java
#   src/main/java/no/ntnu/idatt1002/demo/controller/BudgetController.java
#   src/main/java/no/ntnu/idatt1002/demo/controller/ExpensesController.java
#   src/main/java/no/ntnu/idatt1002/demo/controller/IncomeController.java
#   src/main/java/no/ntnu/idatt1002/demo/controller/MainMenuController.java
#   src/main/resources/Budget/Budget.budget
#   src/main/resources/Economics/Expense.register
#   src/main/resources/Economics/Income.register
#   src/main/resources/view/BudgetNew.fxml
#   src/main/resources/view/Expenses.fxml