Support for passing pandas dataframes to pyplot

[ChakriCherukuri]

Currently pyplot supports passing in numpy arrays and pandas series as data attributes. It'll be nice to support passing in a dataframe and choosing specific columns for data attributes (a la plotly code below)

px.scatter(df, x="sepal_width", y="sepal_length", color="species", size='petal_length', hover_data=['petal_width'])