    link.transition(path, value [, opt])

Allows changing of the link properties gradually over a period of time. This is method is analogous to the transition method of `joint.dia.Element`.

    link.transition('target', { x: 250, y: 250 }, {
        delay: 100,
        duration: 500,
        timingFunction: joint.util.timing.bounce,
        valueFunction: joint.util.interpolate.object
    });
    // will start changing the link target coordinates in 100ms, for period of 500ms and performing a bounce effect.