Assegnate 3 su 5 stelle

https://bugzilla.mozilla.org/show_bug.cgi?id=277731 was fixed.

There remain issues such as
https://bugzilla.mozilla.org/show_bug.cgi?id=445305
https://bugzilla.mozilla.org/show_bug.cgi?id=553158
and I wondered whether this add-on might offer an superior approach in those environments but I guess that the add-on will not be developed for modern versions of Sunbird or Lightning.