save the none to server for non-existing markerEnd
Removes a bug with "markerEnd" in links which was saved as undefined to server when "none" was selected and then on re-load it would be populated with "arrowclosed" which is the default value.
Removes a bug with "markerEnd" in links which was saved as undefined to server when "none" was selected and then on re-load it would be populated with "arrowclosed" which is the default value.