ui: Group graph nodes by file or namespace (issues #171, #439, #522)

* added buttons to enable grouping by file or namespace
* last used group settings saved to ApplicationSettings
* made groups hoverable/clickable on label only
* improved node hatching and override edge colors
* group overview lists

fortune cookie message = Seen with the eyes of love, everything gets a new meaning.

src/lib_gui/qt/view/QtGraphView.h

@@ -61,6 +61,7 @@ public:
 	virtual void resizeView();
 
 	virtual Vec2i getViewSize() const;
+	virtual GroupType getGrouping() const;
 
 	virtual void scrollToValues(int xValue, int yValue);
 
@@ -84,6 +85,8 @@ private slots:
 	void clickedBackwardTrail();
 	void clickedForwardTrail();
 
+	void groupingUpdated(QPushButton* button);
+
 private:
 	MessageActivateTrail getMessageActivateTrail(bool forward);
 	void activateTrail(bool forward);
@@ -153,6 +156,10 @@ private:
 	QSlider* m_trailDepthSlider;
 	QLabel* m_trailDepthLabel;
 
+	QWidget* m_groupWidget;
+	QtSelfRefreshIconButton* m_groupFileButton;
+	QtSelfRefreshIconButton* m_groupNamespaceButton;
+
 	std::vector<QRectF> m_virtualNodeRects;
 
 	// Name matches