GeneralBudget set BudgetPeriod to be days left of month, and made FileHandling methods static.

See merge request !39

Created and implemented addUnusedCategories when switching scenes from budget + catch blocks display alert box

mini progressbars

edit or delete income/expense

Merge branch 'frontend-testing' of gitlab.stud.idi.ntnu.no:andreksv/idatt-1002-2023-9 into frontend-testing

IOexceptions

Added exception to BudgetItem constructor and Overview now takes in a Budget

See merge request !33

Added input validation to add dialog boxes.

See merge request !32

# Conflicts:
#   src/main/java/no/ntnu/idatt1002/demo/controller/AddBudgetController.java
#   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/FinanceController.java
#   src/main/java/no/ntnu/idatt1002/demo/controller/IncomeExpenseController.java
#   src/main/java/no/ntnu/idatt1002/demo/controller/MainMenu.java
#   src/main/java/no/ntnu/idatt1002/demo/controller/SceneController.java
#   src/main/resources/Economics/Income.register
#   src/main/resources/view/IncomeAndExpenses.fxml