Merge branch 'issue20' into 'develop-v2.1.1'

documentation/diagrams/ItemBatch.png

documentation/diagrams/ProductionEquipmentAndFactory.png

documentation/diagrams/S4INMA Factory example.png

documentation/diagrams/S4INMA Item example.png

documentation/diagrams/S4INMA Material example.png

documentation/diagrams/S4INMA Measurement example.png

documentation/diagrams/S4INMA ProductionEquipm example.png

documentation/diagrams/saref4inma.xml

documentation/diagrams/saref4inmaOverview.png

examples/Item.ttl

examples/Material.ttl

ontology/saref4inma.ttl