New features
- copy chart as PNG option in exporting menu
- argument aliases in `chart.vband` and `chart.hband` for `min`, `max` and `color`
- text labels for `chart.vband` and `chart.hband`
- convert integer `color` to `colorIndex`
Deprecations
- `chart.append` is now deprecated
Bug fixes
- `easychart.plot` passes arguments to `easychart.new` based on function signature