Added SDL_DISPLAYEVENT_MOVED to detect when display positioning changes

include/SDL_video.h

@@ -187,7 +187,8 @@ typedef enum
     SDL_DISPLAYEVENT_NONE,          /**< Never used */
     SDL_DISPLAYEVENT_ORIENTATION,   /**< Display orientation has changed to data1 */
     SDL_DISPLAYEVENT_CONNECTED,     /**< Display has been added to the system */
-    SDL_DISPLAYEVENT_DISCONNECTED   /**< Display has been removed from the system */
+    SDL_DISPLAYEVENT_DISCONNECTED,  /**< Display has been removed from the system */
+    SDL_DISPLAYEVENT_MOVED          /**< Display has changed position */
 } SDL_DisplayEventID;
 
 /**