Inferred ObjectProperty hierarchy displays owl:bottomObjectProperty as a leaf node of every node

[matthewhorridge]

The inferred object property hierarchy displays owl:bottomObjectProperty as a leaf node of every node. While this is correct, it isn't good for usability as it clutters the hierarchy. Leaf nodes should properties in the signature of the ontology in the same way that class nodes in the class hierarchy are classes in the signature of the ontology rather than owl:Nothing.