Adding additional figures to the comparison report beyond time series

[ledm]

A couple people have asked for some new figures:

• Hovmoellers for a specific region. (Depth by time figures)
• Surface maps showing several a layer at a point in time for a bunch of individual models. Either totals or differences.

[ledm]

To be this, we'll need to make a whole host of changes to analysis_compare, report maker, and make a couple new plotting functions.