Pick up a common localization file format?

[Gnimuc]

After some investigation, I find it might be good to use some localization service like transifex as our collaboration tool. It has many useful features, for example, when the original source file is updated, it'll automatically cache the old translation:

If we wanna use transifex, the docstrings need to be dumped to a common file format that transifex supports, such as gettext's PO format. It seems PO format is very simple and easy to parse, I'll look into this and check out the feasibility.