- added the `create_histogram` method and the `Histogram` object.
- added the `round` parameter to `trend_line` and `ray_line`
- chart.set can now be given line data.
Bug Fixes:
- `NaN` values can now be given when setting data, and will leave a blank space in the data.
- `resize` will now change the chart wrapper’s size as well as the chart itself.
