Plotters demo

## Smooth Lines

This plotter draws smooth lines between points using bezier curves.

Smoothing: 0.33

View source to see how this works. You'll have to source `extras/smooth-plotter.js` in addition to dygraphs to get this feature. (However, for better browser compatibility, use the file from `src-es5/extras/` (`dist/extras/`) instead.) See the comment from the pull request that introduced this plotter (online) to learn more about how it smooths your curves.