All l10n files should be located within the middlewares l10n folder.

This contains:
- all translation files for text parts: formerly the .po started with 'main-*' they now have to start with 'guard-*'. E. g. main-de_DE.po -> guard-de_DE.po
- all translation files for templates: starting with 'templates-*.po'. E. g. templates-de_DE.po
- languages.xml: to define available languages