Pie chart event handlers not given an eventArgs object.

[brennana]

Greetings,

I created a pie chart and attempted to override getTooltipText() on the series, but the event handler is not given an eventArgs object, so I cannot access properties such as seriesValue.

var ring = svpChart.addSeries("index", dimple.plot.pie);
ring.addOrderRule("index");
ring.innerRadius = "50%";

ring.getTooltipText = function(e) {
    // This is undefined.
    console.log(e.seriesValue);
    return [e.seriesValue];
};

I tried the workaround mentioned in #15, but I could not find the series value I assigned.