Adds support for mouse wheel zooming.
Features
- Added support for mouse wheel zooming.
- Added 'heatmap.interpolation' option for creating smooth heatmaps.
- Added new function: Chart.getOptions(), to get the current active configuration options for the chart.
- Added 'treegraph.fillSpace' option for treegraphs to fill the whole plot area even when some points are collapsed.
- Added 'borderRadius' option support for funnel and pyramid series.