Feature request: implement pybabel lint

[jeanas]

A common error that translators do is translating the format field names, while they should remain untranslated. For example: translating "File {file} not found" by "Fichier {fichier} non trouvé" instead of "Fichier {file} non trouvé".

There is a script in this repository that checks for such errors: https://github.com/himdel/lint-po. However, it does its own PO file parsing that looks a bit fishy. I'd rather have this functionality in babel, with a well-tested PO parser.

[Quix0r]

That would be much appreciated.

[akx]

Sounds like a great idea :)