Filter JoystickEvent.AXIS_MOVE

JoystickEvent.AXIS_MOVE receives updates axis by axis: it was previously sending a JoystickEvent each time, even if no axis values changed. It is now counter-checking incoming values with the previous registered state, only sending the JoystickEvent according to difference in values, avoiding overflow.
Merge pull request #255 from Hasufel/patch-1

Filter JoystickEvent.AXIS_MOVE