Highlight dataset when hovered in legend

[Rednas83]

Feature Proposal

When a dataset is hovered fade the rest of the chart.

Possible Implementation

[LeeLenaleee]

At the moment you can set the active elements which makes the color the current hoverbackgroundColor as shown here https://jsfiddle.net/Leelenaleee/dL2a5n34/18/

[LeeLenaleee]

With the current master you can set the backgroundcollor of all other charts to a more faded while using the onhover and onleave callbacks of the legend.

https://jsfiddle.net/Leelenaleee/mv9L7nh6/