Remove unused custom event
-#define EVENT_NEW_SESSION SDL_USEREVENT
-#define EVENT_NEW_FRAME (SDL_USEREVENT + 1)
-#define EVENT_STREAM_STOPPED (SDL_USEREVENT + 2)
+#define EVENT_NEW_FRAME SDL_USEREVENT
+#define EVENT_STREAM_STOPPED (SDL_USEREVENT + 1)
