Semtools

Currently you can select a subclass of [oboe-core] Measurement and have the other fields populate with a valid class for that field (the Entity, say). But there are cases where there are many valid Entities for a given Measurement and we would only be selecting the first (seems to be alphabetical at this point). What should probably happen is that the selection widget further constrains the ontology browser for that field so that only valid classes (and subclasses) can be selected.