refactor for sdf2marker
works, e.g.
rosrun gazebo2rviz sdf2marker_node.py coke_can
rosrun tf2_ros static_transform_publisher 0 0 0  0 0 0 1 /coke_can world

Not yet sure what is the best way to map model internal names to TF names
actually used in lab ... perhaps they SHOULD be the same anyway