ui: styled nodes in graph view

This change styles the nodes in the QtGraphView. Since Stylesheets can't be applied to QGraphicsItems, the style
implementation was done in the source files. The containers for public/protected/private nodes are now subclassed from
QtGraphNode as QtGraphNodeAccess, including a helper class QtAccessArrow for indicating the opened/colapsed state.

src/lib/component/view/GraphView.h

@@ -11,8 +11,6 @@
 struct DummyEdge;
 struct DummyNode;
 class Graph;
-class GraphEdge;
-class GraphNode;
 
 class GraphView : public View
 {
@@ -29,13 +27,6 @@ public:
 		const std::vector<DummyEdge>& edges) = 0;
 
 	virtual void clear() = 0;
-
-protected:
-	std::shared_ptr<Graph> m_graph;
-	std::vector<Id> m_activeTokenIds;
-
-	std::list<std::shared_ptr<GraphNode> > m_nodes;
-	std::list<std::weak_ptr<GraphEdge> > m_edges;
 };
 
 #endif // GRAPH_VIEW_H