Zoom transitions for treemap

[stevebuik]

Question: which small fns are included in my artifact? Labels are not visible for small cells.

Answer: to aid in visual scanning, support zoom to increase size of cells and make labels appear.

Note the label/name is already available in the tooltip so this is all about visual scanning.

Clicks on any cell in the treemap could Zoom into the group (using the legend grouping) using something like https://bost.ocks.org/mike/treemap. that example allows zoom to N levels deep but even just a single level zoom would help.

[stevebuik]

clicks on the legend could also trigger the top level zoom