pybullet.changeVisualShape(obUid,linkIndex,specularColor=[R,G,B]) and Bullet C-API b3UpdateVisualShapeSpecularColor
Bug fixes in b3ResourcePath::findResourcePath resolution.
add stadium.sdf and roboschool/models_outdoor/stadium assets https://github.com/openai/roboschool/tree/master/roboschool/models_outdoor/stadium
minor fixes to obj2sdf