Stop hijacking SAREF Core terms (saref-portal#48)

From saref-portal#48 (closed)

DisjointFrom axioms may be defined in SAREF extensions, but if they are used, at least one class in the DisjointFrom axiom should be in the namespace of the extension that is under development.

Remove: SAREF4CITY: saref:Measurement owl:disjointWith saref:Property , saref:UnitOfMeasure ; SAREF4CITY: saref:Property a owl:Class ; owl:disjointWith saref:UnitOfMeasure

Changes have to be performed in the OWL code, TS, diagrams and documentation