function endTraversal() {
        var pane = _getPane(ACTIVE_PANE);

        if (_traversingFileList) {
            _traversingFileList = false;

            _makeFileMostRecent(pane.id, pane.getCurrentlyViewedFile());
        }
    }
Un-freezes the MRU list after one or more beginTraversal() calls.
Whatever file is current is bumped to the front of the MRU list.