Uses the object guid to find a rhino object. Deleted objects cannot be found by id. The guid is the value that is stored on RhinoObject.Id In a single document, no two active objects have the same guid. If an object is replaced with a new object, then the guid persists. For example, if the _Move command moves an object, then the moved object inherits it's guid from the starting object. If the Copy command copies an object, then the copy gets a new guid. This guid persists through file saving/opening operations. This function will not find grip objects.