message: gltfpack: Warn about embedded images
  We currently don't support embedded images; they are suboptimal for
  gltfpack in general - ideally they would come as separate Basis-encoded
  files - so for now just warn about them.
  Fixes
diff: @@ -1435,9 +1435,18 @@ bool process(Scene& scene, const Settings& settings, std::string& json, std::str
  const cgltf_image& image = data->images[i];
  comma(json_images);
  - json_images += "{\"uri\":\"";
  + json_images += "{";
  + if (image.uri)
  + {
  + json_images += "\"uri\":\"";
  json_images += image.uri;
  - json_images += "\"}";
  + json_images += "\"";
  + }
  + else
  + {
  + fprintf(stderr, "Warning: image %d has embedded texture data, skipping\n", int(i));
  + }
  + json_images += "}";
  }
  for (size_t i = 0; i < data->textures_count; ++i)
  