QCleanLooksStyle doesn't fully support QProxyStyle

When using QCleanLooksStyle in a QProxyStyle, CleanLooks doesn't support custom PM_SliderThickness nor PM_SliderLength

To reproduce:
subclass QProxyStyle::pixelMetric(...) for the metric QStyle::PM_SliderLength. Set QCleanLooksStyle as the base style for the proxy
-> the slider handle size is not changed

Suggested fix:

In
"QRect QCleanlooksStyle::subControlRect(ComplexControl control, const QStyleOptionComplex *option, SubControl subControl, const QWidget *widget) const",

replace

rect.setHeight(pixelMetric(PM_SliderThickness));
rect.setWidth(pixelMetric(PM_SliderLength));
...
rect.setWidth(pixelMetric(PM_SliderThickness));
rect.setHeight(pixelMetric(PM_SliderLength));

by:

rect.setHeight(proxy()->pixelMetric(PM_SliderThickness));
rect.setWidth(proxy()->pixelMetric(PM_SliderLength));
...
rect.setWidth(proxy()->pixelMetric(PM_SliderThickness));
rect.setHeight(proxy()->pixelMetric(PM_SliderLength));

Note: there is one more missing style()->pixelMetric(...) at line qcleanlooksstyle.cpp:2161