Allow multiples default csv locales

[Levrault]

Hi,

I'm been using the addon for a few day and It really amazing. I just want to propose a small improvement. When creating csv, we can only choose one default csv locales. It force the user to always add multiple new columns in the csv files.

e.g. I want my game to support english, french and spanish. Every time I export a new .dialogue I need to open the csv file and add frand esto tthe csv file.

I propose to allow the user to add multiple locale with the coma delimiter.

I already made quick and dirty implementation to make it works with my project Levrault@6e73a33

Thanks