interactivemarkers: get the correct transformation for sub-markers

tested with http://www.cse.wustl.edu/~dvl1/stuff/marker_marker_marker_frame_bug.zip - submarker now shows up where you'd expect it to
also made sure examples/interactivemarkers.html still works

RE: RobotWebTools/ros3djs#71 - ros3djs now mirrors RViz, but it's unclear if thats ultimately the desired behavior