Fix changing the current dir using the 'recent url' combo box.

Upon accepting new url in the 'directory' url combo box, append '/' if needed: the combo does not add it, but tokenize() expects it because uses KUrl::setFileName(), which would silently remove the last segment of the path.

Without the fix, if you select /home/js/foo/bar from the url combo box, and click on file.txt, the resulting url would be /home/js/foo/file.txt, not the expected /home/js/foo/bar/file.txt.

Another, and hopefully the last place where we have to care about trailing slashes for dirs, is kdiroperator.