add new graphical structure; remains to do the same with collisions
add clean_mesh=True on addCollisionMeshes, avoid segmentation fault for some meshes
add simple Dae loader, does not need to create urdf file
good collision meshes, but problem if many simple shapes: name conflict
modify urdf robots; now meshes positions are correctly defined in their structures
Merge branch 'master' of github.com:XDE-ISIR/XDE-RobotLoader
Merge branch 'devel'

Conflicts:
	src/core.py