[models] Added 3 models of crates

for outdoors or indoors scenes
[models] New improved version of the old 'trees' environments

Use many assets from the yofrankie game + new normal map for dirt
+ crates + new skybox +...
[doc] Updated doc for bounding boxes and passive objects
[media] Added a new screenshot and versions of the MORSE logo
[doc] add rospy example. fixes #272