various french translation improvements

interface/web/admin/lib/lang/fr_users.lng

interface/web/mail/lib/lang/ar_mail_mailinglist.lng

interface/web/mail/lib/lang/bg_mail_mailinglist.lng

interface/web/mail/lib/lang/ca_mail_mailinglist.lng

interface/web/mail/lib/lang/el_mail_mailinglist.lng

interface/web/mail/lib/lang/en_mail_mailinglist.lng

interface/web/mail/lib/lang/fi_mail_mailinglist.lng

interface/web/mail/lib/lang/fr_mail_backup_list.lng

interface/web/mail/lib/lang/fr_mail_mailinglist.lng

interface/web/mail/lib/lang/fr_mail_user.lng

interface/web/mail/lib/lang/hr_mail_mailinglist.lng

interface/web/mail/lib/lang/hu_mail_mailinglist.lng

interface/web/mail/lib/lang/id_mail_mailinglist.lng

interface/web/mail/lib/lang/it_mail_mailinglist.lng

interface/web/mail/lib/lang/ja_mail_mailinglist.lng

interface/web/mail/lib/lang/nl_mail_mailinglist.lng

interface/web/mail/lib/lang/pt_mail_mailinglist.lng

interface/web/mail/lib/lang/ro_mail_mailinglist.lng

interface/web/mail/lib/lang/ru_mail_mailinglist.lng

interface/web/mail/lib/lang/se_mail_mailinglist.lng