add "reverse" update of fan chart

[coret]

A user can click on an ancestor in the fan chart, the chart is then updated where this person becomes the proband (or root). This can be repeated to "zoom in" to deeper parts of the ancestry.

But, there is currently no means to reverse this process, eg. you can't click back to the "original" root. Maybe attach an right-click event to the root person of the chart which calls a "zoom out" function?

[ekdahl]

This is a feature I also miss. Need to update the page to get back.

[ekdahl]

Here's an example of a wheel that can zoom out: https://www.jasondavies.com/coffee-wheel/
It also has some nice animations when zooming.