0.0.04

- put fonts in Reference class
- made GUI parent class to make making GUIs easier
- put exit button in GUI parent class
- made GUI for bluetooth (not done and is for testing right now)
- removed add/remove MainGUI methods from Window class
- made MainGUI get added in MainClass
- made a button to go to Bluetooth GUI

BUGS
- exit button doesn't show up on main screen