Enhancement: Native support for events

[Zeioth]

Currently the only supported events are:
Chart: Hover and click
Legend: Click

It would be great to have native support for:
Chart: mouseout
Legend: mouseout, hover

This should cover 90% of the most common interactions without 'out of the box' hacks.
Thank you so much for your great job guys.

[etimberg]

Tied in with #2903

If someone wants to implement this, please ping one of the maintainers to discuss design first.

[etimberg]

Now that #3718 was merged, it is possible to write a plugin that handles events of any type. This makes it possible to do this.