-- TODO --

 - sell large scale sims to industry?
 - 0.01M robots
 - pacman world

 - boundary property

 - sensible defaults - laser (all devices)
    - where to put default values? in each model seems better than the
      header file

 - docs

 - energy

 - pucks

 - gripper 


-- DONE --

 - collapse all stg_X player drivers into a single driver with
multiple interfaces. See note in stg_driver.cc
