API Discussion for Figures and Axes

This issue is to discuss the open letter regarding Yellowbrick’s API roadmap. To summarize, we currently attempt to only manage matplotlib Axes objects so that visualizers can be embedded into more complex plots and reports. However, many of our visualizers are getting increasingly complex, requiring subplots of their own. For a complete discussion of the API issue please see:

https://www.scikit-yb.org/en/develop/api/figures.html

The questions at hand are:

1. Like Seaborn, should YB have two classes of visualizer, one that wraps an axes and one that wraps a figure?
2. Should we go all in on the AxesGrid toolkit and continue to restrict our use of the figure, will this method be supported in the long run?

[bbengfort]

@rebeccabilbro I think this will require us to modify our matplotlib dependency to 2.0.2 or later.

[bbengfort]

In #957 we added a Visualizer.fig and updated the dependency to 2.0.2 or later. These changes along with this excellent discussion has moved us forward to our v1.0 release and v1.1 will include more robust support for multi-Axes figures and quick methods.