implemented scroll wheel zooming in all TimelineViewBase derivatives

app/widget/keyframeview/keyframeview.cpp

@@ -6,6 +6,13 @@ KeyframeView::KeyframeView(QWidget *parent) :
   setAlignment(Qt::AlignLeft | Qt::AlignTop);
 }
 
+void KeyframeView::wheelEvent(QWheelEvent *event)
+{
+  if (!HandleZoomFromScroll(event)) {
+    KeyframeViewBase::wheelEvent(event);
+  }
+}
+
 void KeyframeView::AddKeyframe(NodeKeyframePtr key, int y)
 {
   QPoint global_pt(0, y);

app/widget/keyframeview/keyframeview.h

@@ -9,6 +9,9 @@ class KeyframeView : public KeyframeViewBase
 public:
   KeyframeView(QWidget* parent = nullptr);
 
+protected:
+  virtual void wheelEvent(QWheelEvent* event) override;
+
 public slots:
   void AddKeyframe(NodeKeyframePtr key, int y);