Add draw grid button

src/imagescrollarea.cpp

@@ -142,6 +142,11 @@ void ImageScrollArea::falseColor(bool enable)
     m_imageWidget->falseColor(enable);
 }
 
+void ImageScrollArea::drawGrid(bool enable)
+{
+    m_imageWidget->drawGrid(enable);
+}
+
 QImage ImageScrollArea::renderToImage()
 {
     return m_imageWidget->renderToImage();