i18n-it: translate [OPTION]..., not [OPTIONS]...: keep the singular
Since [OPTION]... is intended to mean more options, it was translated in Italian
as plural. However the plural is conveyed by `...', so switch to the singular.
This was also useful because for the '-o OPT' extdiff option, I have to
translate `OPT' as a singular.
i18n-it: readd other lost accented characters
The problem was introduced already in revision
9f9137cd83f5 by the original
Italian translator, according to logs. This might be due to a bug in the program
he used, "Lokalize 0.3", or maybe not - some accented characters exist also in
that commit.