Add option for specifying the CSV delimiter char

[estellecomment]

Hello !

I am considering using your neat little package for a project, and my CSV file had a weird delimiter character, so I added the option to specify the delimiter. I hope this can be of value for you !

Note : my editor has removed all trailing whitespace, which can be annoying when you view the diff. If it provides no value to you I could go back and re-add the whitespace I suppose.

Thank you for providing this package !