Also remove <intl include="Translations/locale.xml"/> from
preferences.xml. Something equivalent based on readProperties() is done
in FlightGear (cf. FGLocale::FGLocale() in
flightgear/src/Main/locale.cxx).
Add the translation for the <download-dir-desc> switch and update the one
for the <metar-desc> one.
Also change "tempo" to "orario" in menu.xml to be consistent with the
term choice in options.xml.
Run script to identify missing/obsolete items:
de/options.xml is missing 192 translation(s).
de/menu.xml is missing 20 translation(s).
es/options.xml is missing 12 translation(s).
es/menu.xml is missing 78 translation(s).
fr/options.xml is missing 0 translation(s).
fr/menu.xml is missing 0 translation(s).
it/options.xml is missing 212 translation(s).
it/menu.xml is missing 78 translation(s).
nl/options.xml is missing 54 translation(s).
nl/menu.xml is missing 1 translation(s).
pl/options.xml is missing 81 translation(s).
pl/menu.xml is missing 76 translation(s).
pt/options.xml is missing 212 translation(s).
pt/menu.xml is missing 86 translation(s).
