Xy chart tooltip in zoom mode

• Fixed wrong targeted index in zoom mode

Zoom functionality in xy chart

• Added click and drag to zoom on xy chart
• Added zoomColor general option in xy chart

Improved Gauge chart

• dataLabels options

Donut & Gauge charts

• gauge chart
• updated tests
• shape-rendering chart global option
• exposed css classes

Foundations

Tested and workable version including:

• xy chart
• donut chart
• low level svg api, dog fed to build the charts :)