Reworked the joystick idea

- New joystick mapping class (holds the button numbers, etc)
- MyJoystick now keeps its state and has an isPressed() method
- Headers are written to the pickle file, but Plot.py  ignores them during
  the zip()
- New PilotJoystick class with trpy fraction methods and button methods
  (switchPressed, killPressed, etc)
- The pilot that the joystick is now called ManualPilot (to avoid
  confusion with PilotJoystick)