builder: output translated notes

Output all the translations available for the notes in the "verbose"
output and the JSON output, while trying to match the system langauge in
the "show notes" output.

The JSON output is slightly changed to handle translations, with the
"untranslated" notes being matched as "C". The version is not bumped
though, since there have been no stable releases with the former output
yet.
builder: remove unused variables

Leftovers of the list_entries_short+list_entries_long split done in
commit 91aae893c70b3877b31803800ba77836fd7a45e8.