message: fix memory leak, reprUpdatedSubscriptions not removed
diff: @@ -298,6 +298,8 @@ namespace Canvas3D {
  }
  },
  clear: () => {
  + reprUpdatedSubscriptions.forEach(v => v.unsubscribe())
  + reprUpdatedSubscriptions.clear()
  reprRenderObjects.clear()
  scene.clear()
  debugHelper.clear()
  