\n within fields

[mdlincoln]

It's probably worth warning the user that they will find \n interspersed in the provenance fields, as this can (annoyingly) choke some CSV parsers. Do line breaks occur in any other fields?

[workergnome]

A quick scan says that `provenance_text,medium``, and``credit_line`` currently all have newlines in their text. Will add a note about that into the Readme.

[workergnome]

Thanks!