Add custom csv delimiter option
Hi there, you'll have to forgive me for this is my very first Python PR. I may be completely unawares of how you can pull this off in another way. If anything whatsoever needs changing, know you're talking to a Python n00b, but a professional programmer.
Anyway, I was finding myself in need of this functionality as I had fields with , in them, pesky formatted currencies for example.
I'm by no means a 🐍 Wizard and I enjoyed stumbling upon this project to learn how to do basic things. Including Unit Tests and a bunch of other concepts I would use in Swift/Obj-C/JavaScript. The project is well laid out and with reasonably sized clean functions, and tests!
I did consider refactoring how the CSV writing occurred, so that the Unit Tests didn't have to rely on an outputted file, nor having to cleanup afterwards. But wanted to see if this would pass.