various: implement sequence pixel aspect ratios and interlacing settings

Implements the following:
- Sequences have pixel aspect ratios that work in tandem with footage PARs
  to render footage correctly. Viewer and export also acknowledge PARs
- Sequences can have interlacing settings. This doesn't do anything yet,
  eventually the renderer will need to interlace/deinterlace/reinterlace
  appropriately in order to conform all the footage to the sequence. Export
  acknowledges interlacing, but this only affects metadata, not the image.

app/render/pixelformat.cpp

@@ -263,8 +263,8 @@ FramePtr PixelFormat::ConvertPixelFormat(FramePtr frame, const PixelFormat::Form
   // Create a destination frame with the same parameters
   FramePtr converted = Frame::Create();
   converted->set_video_params(VideoParams(frame->video_params().width(),
-                                                   frame->video_params().height(),
-                                                   dest_format));
+                                          frame->video_params().height(),
+                                          dest_format));
   converted->set_timestamp(frame->timestamp());
   converted->allocate();