Add context menu option to save images

fixes #265

include/timeline/TimelineItem.h

@@ -99,6 +99,8 @@ protected:
 
 private:
         void init();
+        //! Add a context menu option to save the image of the timeline item.
+        void addSaveImageAction(ImageItem *image);
 
         template<class Widget>
         void setupLocalWidgetLayout(Widget *widget,

include/timeline/widgets/ImageItem.h

@@ -48,6 +48,10 @@ public:
 
         QSize sizeHint() const override;
 
+public slots:
+        //! Show a save as dialog for the image.
+        void saveAs();
+
 protected:
         void paintEvent(QPaintEvent *event) override;
         void mousePressEvent(QMouseEvent *event) override;