Support rotated labels

Release 0.5

• Support rotated labels

Support for Sunburst charts

• Support for Sunburst charts (variable depth multi-level pie charts)
• Support for gradient colors
• Few more configuration options

Support same depth multi-level pie charts with drill-down ability

Release 0.2

• Support same drill-down depth multi-level pie charts
• Support drill-down by double-clicking a pie slice
• Support various configuration options