This method is the same for all elements and can be implemented in the 
parent.

This may happen when changing the Clote document property.

Also move cloze-code into Cloze and no longer have it in a general 
purpose service.

The default value of the child class overrides the value set by the 
parent constructor.

#700

- Image
- Hotspot-Image
- Audio
- Video
- Geometry
- DragNDropValueObject (imgFileName, audioFileName)
- LikertRowElement (imgFileName, audioFileName)

Just ignore the color in the component.

- remove 'own' as possible connection

- remove 'none'

For Table compatibility.

Dimensions are mandatory but with only height and width.

This change is for GeoGebra-Elements, which have mandatory width and 
height.