Method chainable LOD.addLevel()

src/objects/LOD.js

@@ -66,7 +66,7 @@ LOD.prototype = Object.assign( Object.create( Object3D.prototype ), {
 
 		levels.splice( l, 0, { distance: distance, object: object } );
 
-		this.add( object );
+		return this.add( object );
 
 	},