Adding global_calibration for finding the relative position of the camera inside the robot.

Change-Id: I98a9fb4544f17969c47b519114fb8ecf8e412329
diff --git a/aos/vision/image/image_dataset.h b/aos/vision/image/image_dataset.h
index ce8c841..7801cec 100644
--- a/aos/vision/image/image_dataset.h
+++ b/aos/vision/image/image_dataset.h
@@ -15,6 +15,8 @@
 
 std::vector<DatasetFrame> LoadDataset(const std::string &jpeg_list_filename);
 
+DatasetFrame LoadFile(const std::string &jpeg_filename);
+
 }  // namespace vision
 }  // namespace aos