A single line link.

Supported `attrs` properties

Selector | Node | Description
--- | --- | ---
root | SVGGElement | Container of all nodes
line | SVGPathElement | Visible connection of the link
wrapper | SVGPathElement | Invisible wrapper around the connection to make the line thicker, so the user can interact with the link more easily.

    var link = new joint.shapes.standard.Link();
    link.prop('source', { x: 450, y: 600 });
    link.prop('target', { x: 400, y: 750 });
    link.prop('vertices', [{ x: 450, y: 700 }]);
    link.attr('root/title', 'joint.shapes.standard.Link');
    link.attr('line/stroke', '#fe854f');
    link.addTo(graph);