Individuals by Type view should allow empty classes to be added to the view

[matthewhorridge]

At the moment, it is cumbersome to add and type individuals with a type that doesn't already appear in some other class assertion. For example, if the ontology contains ClassAssertion(:A :i) then the class A will appear in the view, but if the user wants to add ClassAssertion(:B :k) and the ontology does not contain class assertions with B then they have add k at the top level and then assign a type on the right hand side. It would be better if this was possible in the actual view.