* keep Slic3r in tooltip, as it's replaced
* use %S or %1% to set the name of the software in other places.
* pom_merger now don't save empty translations.
* pom_merger now can propose similar but not identical translations, to be able to copy & modify them
* pom_merger now can add language to header via a setting.
* github actions will now compile the pot each time. No need to store it in github
* fix pom_merger
* pom_merger now sort the entries, add a header to localization .po file
so the utf-8 encoding is correctly detected by the gettext util, and can
delete comments
* update ru, it & fr files
