String encapsulation for improved translation

Or we could adopt [the same i18n scheme as Qt](http://qt-project.org/doc/qt-4.8/internationalization.html#use-qstring-arg-for-dynamic-text): `"page %1 of %2"`. This way translators which are already familiarized to such notation would have no difficulties, and there would be no risk of using the wrong `｛｝` characters.