py: Add FrameMetadataPlane

Add FrameMetadataPlane class and adjust the methods and uses
accordingly.

Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

src/py/cam/cam.py

@@ -285,7 +285,8 @@ class CaptureState:
             print('{:.6f} ({:.2f} fps) {}-{}: seq {}, bytes {}, CRCs {}'
                   .format(ts / 1000000000, fps,
                           ctx.id, stream_name,
-                          meta.sequence, meta.bytesused,
+                          meta.sequence,
+                          '/'.join([str(p.bytes_used) for p in meta.planes]),
                           crcs))
 
             if ctx.opt_metadata: