Add very basic chart support

examples/xlsx/chart/chart.pro

@@ -0,0 +1,9 @@
+TARGET = chart
+
+#include(../../../src/xlsx/qtxlsx.pri)
+QT+=xlsx
+
+CONFIG   += console
+CONFIG   -= app_bundle
+
+SOURCES += main.cpp

examples/xlsx/chart/main.cpp

@@ -0,0 +1,31 @@
+#include <QtCore>
+#include "xlsxdocument.h"
+#include "xlsxpiechart.h"
+#include "xlsxworksheet.h"
+
+using namespace QXlsx;
+
+int main()
+{
+    //![0]
+    Document xlsx;
+
+    Worksheet *sheet = xlsx.currentWorksheet();
+    for (int i=1; i<10; ++i)
+        sheet->write(i, 1, i*i);
+    //![0]
+
+    //![1]
+    PieChart *chart = new PieChart;
+    chart->addSeries(CellRange("A1:A9"), sheet->sheetName());
+    sheet->insertChart(3, 3, chart, QSize(300, 300));
+    //![1]
+
+    //![2]
+    xlsx.saveAs("Book1.xlsx");
+    //![2]
+
+    Document xlsx2("Book1.xlsx");
+    xlsx2.saveAs("Book2.xlsx");
+    return 0;
+}