message: Make overlay Add/Remove/Refresh methods accessible from Blueprints.
diff: @@ -42,6 +42,7 @@ public:
  * overlay is already added or if this component's Owner is not a Cesium 3D
  * Tileset, this method does nothing.
  */
  + UFUNCTION(BlueprintCallable, Category = "Cesium")
  void AddToTileset();
  /**
  @@ -49,11 +50,13 @@ public:
  * overlay is not yet added or if this component's Owner is not a Cesium 3D
  * Tileset, this method does nothing.
  */
  + UFUNCTION(BlueprintCallable, Category = "Cesium")
  void RemoveFromTileset();
  /**
  * Refreshes this tileset by removing and re-adding it.
  */
  + UFUNCTION(BlueprintCallable, Category = "Cesium")
  void Refresh();
  UFUNCTION(BlueprintCallable, Category = "Cesium")
  