ui: redesigned graph overview and use new list layouting within overview bundles

* overview bundles imitate style of bundled node type
* removed bundle for built-in types
* show contents of overview bundle in vertical list layouted with new ListLayouter
* nodes starting with the same letter are grouped with the letter displayed above
* pressing the letter key will scroll to the group
* also use this list layouting for namespace & package contents
* renamed BucketGrid to BucketLayouter
* moved used functions of GraphPostProcessor to GraphViewStyle and removed GraphPostProcessor

fortune cookie message = Don't be afraid to take that big step

src/lib_gui/qt/view/QtGraphView.h

@@ -49,9 +49,10 @@ public:
 	virtual Vec2i getViewSize() const;
 
 private slots:
-	void centerScrollBars();
+	void updateScrollBars();
 	void finishedTransition();
 	void clickedInEmptySpace();
+	void pressedCharacterKey(QChar c);
 
 private:
 	void switchToNewGraphData();
@@ -112,6 +113,8 @@ private:
 	std::list<std::shared_ptr<QtGraphNode>> m_oldNodes;
 
 	std::shared_ptr<QtGraphNode> m_activeNode;
+	bool m_scrollToTop;
+	bool m_isIndexedList;
 
 	std::shared_ptr<QSequentialAnimationGroup> m_transition;
 	QPointF m_sceneRectOffset;