s/print/Output.debug/
Debug-Mode can now be toggled from inside the app by pressing Shift-D. Closes #7.
'Press space to continue' on wait-events is now 'Press any key to continue'. Closes #6.
IMAGE_SIZE is now dynamically calculated. Closes #13.
Debug output on screen resulted in a race condition with multiple instances of debug output overlapping on screen. As a fix we update the debug stuff only when we're running in the MainThread.