Possible to smooth lines in linechart?

Was reading up on D3 and spotted [this post](http://www.d3noob.org/2013/01/smoothing-out-lines-in-d3js.html).

Is there an easy way to apply the line.interpolate("effect") to a cedar chart?


```
var valueline = d3.svg.line()
.interpolate("basis") // <=== THERE IT IS!
.x(function(d) { return x(d.date); })
.y(function(d) { return y(d.close); });
```


Start by tracing how Cedar creates its line charts and compare that path with the D3 line generator example in the issue, especially the interpolate setting. Determine where a smoothing option would belong and define done as applying the requested interpolation to a Cedar line chart without breaking existing chart behavior.

Written by the indexing model from the issue text.