Fix Issue1: Add insert_image() function

examples/xlsx/image/image.pro

@@ -0,0 +1,6 @@
+TARGET = image
+
+#include(../../../src/xlsx/qtxlsx.pri)
+QT += xlsx
+
+SOURCES += main.cpp

examples/xlsx/image/main.cpp

@@ -0,0 +1,25 @@
+#include <QtGui>
+#include "xlsxworkbook.h"
+#include "xlsxworksheet.h"
+
+#ifdef Q_OS_MAC
+#  define DATA_PATH "../../../"
+#else
+#  define DATA_PATH "./"
+#endif
+
+int main(int argc, char** argv)
+{
+    QGuiApplication(argc, argv);
+
+    QXlsx::Workbook workbook;
+    QXlsx::Worksheet *sheet = workbook.addWorksheet();
+    QImage image(400, 300, QImage::Format_RGB32);
+    image.fill(Qt::green);
+    sheet->insertImage(5, 5, image);
+
+    workbook.save(DATA_PATH"Test.xlsx");
+//    workbook.save(DATA_PATH"Test2.zip");
+
+    return 0;
+}

examples/xlsx/xlsx.pro

@@ -1,4 +1,5 @@
 TEMPLATE = subdirs
 SUBDIRS = hello style \
-    documentproperty
+    documentproperty \
+    image