feat(dataframe): display original dataframes in compare

[azachar]

Hi there!

Thank you very much for your great library.

In order to debug faster and see what went wrong, I came up with a simple solution of displaying original df1 and df2.

The way how the pretty table is showing difference is sometimes very hard to read, this workaround would increase the readability.

Let me know if you have any ideas how to make better.

Cheers, Andrej

[azachar]

Meanwhile I have reworked it further and created a new UI, look at the branch feature/color:

In the readme I have noticed how to install this fork.

I look forward for your feedback.

Cheers, Andrej