Reduce ImageMatchResult space usage

We were using the non-recursive version which depends on the memory
layout of all the original flatbuffer.  Instead, copy things over piece
by piece.  This recompacts everything.

Change-Id: Ib975918d4938c7b4303a77889dec0e5499962653
diff --git a/y2020/vision/camera_reader.cc b/y2020/vision/camera_reader.cc
index fd79d09..24e9ae1 100644
--- a/y2020/vision/camera_reader.cc
+++ b/y2020/vision/camera_reader.cc
@@ -212,7 +212,7 @@
     aos::Sender<sift::ImageMatchResult> *result_sender, bool send_details) {
   auto builder = result_sender->MakeBuilder();
   const auto camera_calibration_offset =
-      aos::CopyFlatBuffer(camera_calibration_, builder.fbb());
+      aos::RecursiveCopyFlatBuffer(camera_calibration_, builder.fbb());
 
   flatbuffers::Offset<flatbuffers::Vector<flatbuffers::Offset<sift::Feature>>>
       features_offset;