Axis label multiple levels for more dimension

[Parker Kain]

Task:
If there are multiple dimensions on axis we should show the labels for all dimensions instead of selecting one with labelLevel parameter

This can be replicated by following the plots in the sorting tutorial notebook.

As you follow along, the second to last plot looks like this:

and the final plot looks like:

Here - I think ideally, the final plot would have multi-tiered x axis labels, as by default it is impossible to know what each of the Genre bars within a Kind represent.

[Laszlo Simon]

There should be two different types of multi level axis labels:

• nested:

A   B   C   A   B   C 
    X           Y

• flattened:

X,A X,B X,C Y,A Y,B Y,C