hoping for better performance. On this occasion, add context menu
containing "Open" and "Choose folder" enabling drive changes on
Windows. Purge remains of QDirModel elsewhere.
Task-number: QTCREATORBUG-62
Introduce new QString id() const-API and sort wizards by
[untranslated] category and id. Introduce respective constants.
Rubber-stamped-by: con <qtc-committer@nokia.com>