FE/Qt: language string updates.
FE/Qt: updated NLS from 4.1.
FE/Qt4-NLS: merged nl and ko.
FE/Qt4-OSX: fix the translation of the application menu
FE/Qt4-NLS: Merged Czech & Dutch.
FE/Qt4-NLS: Merged Dutch.
FE/Qt4-NLS: Merged Dutch, Spanish, Slovak & Romanian translations.
FE/Qt4-NLS: updated qt_* translation files to 4.4.3
renamed VirtualBox4 to VirtualBox
purge the obsolete Qt3 GUI
FE/Qt: Updated Spanish and Polish translations; Added Dutch translation.