Move private members into d pointer, remove unused signal,
rename clearView() method & clear() signal to clearData(), dataCleared()
Change-Id: I0baf78107861a469185c736fc448b4d3a7929cdd
Reviewed-on: http://codereview.qt.nokia.com/2691
Reviewed-by: Kai Koehne <kai.koehne@nokia.com>