Add joystick debug window
Use table to show Joystick values
Refactor joystick debug update functions
Add combo box showing the connected joysticks
Use the SDL_GameController API
Remove obsolete joystick.* references
Remove XBox controller mapping line

No mapping is needed if XInput is used.
Snap analog stick input to 0
Add support for selecting the gamepad

Not tested - I don't own multiple gamepads.
Fix warnings about main redefinition
Move Gamepad handling to the MainWindow
Add MovementController

This class will calculate and relay the gamepad input to the API.
Add GlobalCalibrationWidget