frame: implemented usage of linesizes

Frame will transparently use an optimized linesize for it's allocated data.

app/codec/frame.h

@@ -47,6 +47,7 @@ public:
   const VideoRenderingParams& video_params() const;
   void set_video_params(const VideoRenderingParams& params);
 
+  int linesize() const;
   const int& width() const;
   const int& height() const;
   const PixelFormat::Format& format() const;
@@ -122,6 +123,8 @@ private:
 
   rational sample_aspect_ratio_;
 
+  int linesize_;
+
 };
 
 OLIVE_NAMESPACE_EXIT