Rated 5 out of 5 stars

Good idea!
I have been waiting for such an extension for a long time!

Beside, I would like to provide it with the translation into Italian.
As it is very simple (just a couple of strings) I put it below. Please note that I give 2 versions of the translation because I don't know if the apostrophe (') should be escaped or not.

Version *WITHOUT* "escape":
{
"extensionDescription": {
"message": "Aggiunge un'opzione al menu contestuale delle cartelle di posta per spostare nel cestino tutti i messaggi ivi contenuti"
},
"contextTitle": {
"message": "Svuota cartella"
}
}

Versione *WITH* "escape" (\)
{
"extensionDescription": {
"message": "Aggiunge un\'opzione al menu contestuale delle cartelle di posta per spostare nel cestino tutti i messaggi ivi contenuti"
},
"contextTitle": {
"message": "Svuota cartella"
}
}

Regards,
Topoldo

This review is for a previous version of the add-on (1.0). 

Thank you for your contribution. I suppose the version without escaped apostrophe works fine. It is now included in the new version.