ui: Improved QtCodeView to annotate code

Added some features to QTCodeSnippet:
* Code is now annotated using information from TokenLocationFile
* Start of line numbering can be set
* Clicking on an annotation in the code gives the corresponding Token Id

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src/app/qt/element/QtCodeSnippet.h

@@ -0,0 +1,71 @@
+#ifndef QT_CODE_SNIPPET_H
+#define QT_CODE_SNIPPET_H
+
+#include <vector>
+
+#include <QPlainTextEdit>
+#include <QObject>
+
+#include "utility/types.h"
+
+class QPaintEvent;
+class QResizeEvent;
+class QSize;
+class QtCodeView;
+class QWidget;
+class TokenLocationFile;
+
+class QtCodeSnippet: public QPlainTextEdit
+{
+	Q_OBJECT
+
+public:
+	class LineNumberArea: public QWidget
+	{
+	public:
+		LineNumberArea(QtCodeSnippet *codeSnippet);
+		virtual ~LineNumberArea();
+
+		QSize sizeHint() const;
+
+	protected:
+		void paintEvent(QPaintEvent *event);
+
+	private:
+		QtCodeSnippet *m_codeSnippet;
+	};
+
+	QtCodeSnippet(QtCodeView* parentView, int startLineNumber, QWidget *parent = 0);
+	virtual ~QtCodeSnippet();
+
+	void lineNumberAreaPaintEvent(QPaintEvent *event);
+	int lineNumberAreaWidth();
+
+	void annotateText(const TokenLocationFile& locationFile);
+
+protected:
+	void resizeEvent(QResizeEvent *event);
+
+private slots:
+	void updateLineNumberAreaWidth(int newBlockCount);
+	void updateLineNumberArea(const QRect &, int);
+	void clickTokenLocation();
+
+private:
+	struct Annotation
+	{
+		int start;
+		int end;
+		Id tokenId;
+	};
+
+	int toTextEditPosition(int lineNumber, int columnNumber) const;
+
+	QWidget *m_lineNumberArea;
+	QtCodeView* m_parentView;
+
+	const int m_startLineNumber;
+	std::vector<Annotation> m_annotations;
+};
+
+#endif // QT_CODE_SNIPPET_H