The STL importer is actually creating an object of its own class, and cannot be manipulated like a mesh. I'm going to modify that importer so it produces meshes instead. At the moment, you can import obj files instead. However, we also need to expose surfaces in python (meshes are collections of surfaces), which are the classes which expose the underlying vertices and triangles. Without this, you will not be able to do the geometry tests in python (the API is available in C++ though, see https://documentation.samson-connect.net/developers/latest/api/classSBMVisualModelSurface/)
