Check button states during update

[Yuri Pourre]

This is a convenient logic that can be abstracted to the listener.

When the update method is called, we should compare the current button states to the previous states of each button (for each controller). Then if there are any changes to the state, we should call the proper method on the listener e.g:

if (button[i] != prevButton[i]) {
  if (button[i])
    this.buttonDown(controller, button[i]);
  else
    this.buttonUp(controller, button[i]);
}

//buttonDown->listener?.buttonDown