ENH: improve figure legend

[wiheto]

Make it possible for the discrete legend to be bigger.

Some ideas:

Allow legend_size = ‘large’ to span all subplots. Alternatively, allow the legend to be longer

Have an argument like legend_discrete_Boer row to allow multiple rows and set it to 3 or 4

Make default text higher

Try and detect when text overlaps.

None of these are decided, just writing notes to myself (and allowing others to contribute idea about how to make them better)