RRDataContainer.get_df doesn't do anything

[barkls]

right now, calling RRDataContainer.get_df() is the same as calling RRDataContainer.dataframe.

I'm guessing that maybe you want users to call get_df() to prevent them modifying RRDataContainer.dataframe. If not, feel free to ignore the rest of this message. If you are trying to prevent modification of dataframe itself, you should rename RRDataContainer.dataframe as RRDataContainer._dataframe (attributes beginning with an underscore are not user-facing in python). You can also use a @property decorator to avoid the need for an empty open-close parentheses. See documentation for more details.

[JWatsonDaniels]

fixed in #13