The dependencies on QFont, QBrush, QIcon are all in QtGui, so there's
little sense to still have these classes in QtWidgets.
This also copies and pastes a version of QWidgetItemData as
QStandardItemData inside qstandarditemmodel_p.h.
Change-Id: Ibafc5a30748e7ce0b54753309ae6dc4a797fc20e
Reviewed-by: Kent Hansen <kent.hansen@nokia.com>