Plotting ExtensionArrays
I'd like to plot data from an ExtensionArray. This currently results in an error `TypeError: Empty 'DataFrame': no numeric data to plot`

This is because the EA data is filtered out. Adding the ExtensionDtype to the filter criteria makes the plot work.
https://github.com/pandas-dev/pandas/blob/master/pandas/plotting/_core.py#L367 

```python3
numeric_data = data.select_dtypes(include=[np.number,
                                               "datetime",
                                               "datetimetz",
                                               "timedelta", 
                                               pint.PintType])

```

Could we get a property of the ExtensionDtype that flags the dtype as holding plotable numeric data?