SpinSlider and ScrollSpinBox read-only support

PIVariantEdit - support for read-only for all types
PIValueTreeEdit - drop Parent grouping, default now Groups, full grouping control, global read-only support, fix new label error

libs/widgets/spinslider.h

@@ -77,6 +77,9 @@ public:
 	bool invertedAppearance() const { return slider->invertedAppearance(); }
 	bool squareScale() const { return square; }
 
+	void setReadOnly(bool r);
+	bool isReadOnly() const { return m_read_only; }
+
 	void setSingleStep(double step) {
 		spin->setSingleStep(step);
 		slider->setPageStep(qRound(step * delim));
@@ -134,7 +137,7 @@ private:
 
 	double min_, max_, val_, delim, page;
 	int dec_, ticks_;
-	bool adjusting, square;
+	bool adjusting, square, m_read_only = false;
 	QSlider * slider;
 	QDoubleSpinBox * spin;
 	QBoxLayout * layout;