Refactor Core model to remove UI things

[wwaites]

The core model is said to be the foundation upon which domain models are built. However, it contains a lot of things like,

:height
    a owl:DatatypeProperty ;
    rdfs:comment "The height of an asset group in the UI" ;
    rdfs:domain :AssetGroup ;
    rdfs:label "hasHeight" ;
    rdfs:range xsd:integer .

:hidden
    a owl:DatatypeProperty ;
    rdfs:comment "Whether a relation is hidden from the UI entirely. This is different from being invisible: a relation is visible (on the canvas) iff both its source and target asset are visible. A hidden relation is *never* visible; neither on the canvas nor anywhere else. This normally applies to relations that are used internally by the validator. All hidden relations are also immutable (by the user)." ;
    rdfs:domain owl:ObjectProperty ;
    rdfs:label "hidden" ;
    rdfs:range xsd:boolean ;
    rdfs:subPropertyOf :immutable .

:isCalculatingRisk
    a owl:DatatypeProperty ;
    rdfs:comment "Whether the risk calculation for this model is currently running" ;
    rdfs:label "isCalculatingRisk" ;
    rdfs:range xsd:boolean .

whilst these predicates certainly belong somewhere, that place would seem to be somewhere that is not the core model.