Bug unified diff format does not work

[jiangtianli91]

I tried unified diff-format but the flag is not interpreted correctly. I also put the flag at the end, but this just gives the default format

$ excel_cmp --diff-format=unified all_stimuli.xlsx all_stimuli_cleaned.xlsx
File: --diff-format=unified does not exist.

[tangruize]

The readme file has a typo. It should be --diff_format=unified as explained in the release page.