ui: Show call graphs, inheritance trees and include trees for active symbol (issue 249 337)

* Added TrailLayouter with Sugiyama dependency layouting
* Layouter supports horizontal and vertical layouts
* Added basic ui to graph view for showing incoming and outgoing paths
* Added depth slider, with infinity at maximum
* Disable trail ui when not available
* Added trail messages to undo stack and only use last one when undoing
* Added QtGraphLineBezier for trail graphs and refactored other line types
* Disabled edge activation for trail layouts, shown only visually
* Highlight all connected edges when hovering a node in trail layout
* Use different color when highlighting call edges for better contrast
* Fixed BucketLayouter issue when edge does not leave node
* Increased click area for angled edges

bug id = 249 337

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src/lib_gui/qt/graphics/QtLineItemStraight.h

@@ -0,0 +1,20 @@
+#ifndef QT_LINE_ITEM_STRAIGHT_H
+#define QT_LINE_ITEM_STRAIGHT_H
+
+#include <QGraphicsItem>
+
+#include "component/view/GraphViewStyle.h"
+
+class QtLineItemStraight
+	: public QGraphicsLineItem
+{
+public:
+	QtLineItemStraight(QGraphicsItem* parent);
+	virtual ~QtLineItemStraight();
+
+	void updateLine(Vec2i origin, Vec2i target, GraphViewStyle::EdgeStyle style);
+
+	virtual QPainterPath shape() const;
+};
+
+#endif // QT_LINE_ITEM_STRAIGHT_H