viewer: use internal texture to allow viewer to control texture as part of its

context

More intuitive code flow and allows the user to undock the viewer (which
forcibly destroys and recreates the context) and the viewer will handle
creation of the new texture in said new context.

app/widget/viewer/viewer.h

@@ -72,15 +72,6 @@ public:
   VideoRenderBackend* video_renderer() const;
 
 public slots:
-  /**
-   * @brief Set the texture to draw and draw it
-   *
-   * Wrapper function for ViewerGLWidget::SetTexture().
-   *
-   * @param tex
-   */
-  void SetTexture(OpenGLTexturePtr tex);
-
   void Play();
 
   void Pause();
@@ -166,7 +157,6 @@ private:
 private slots:
   void PlaybackTimerUpdate();
 
-  void RendererCachedFrame(const rational& time, QVariant value, qint64 job_time);
   void RendererCachedTime(const rational& time, qint64 job_time);
 
   void SizeChangedSlot(int width, int height);