message: gltfpack: Don't emit empty arrays
  For some reason, arrays are specified as containing 1+ elements in GLTF;
  let's stop emitting empty arrays then.
diff: @@ -1959,30 +1959,7 @@ bool process(Scene& scene, const Settings& settings, std::string& json, std::str
  json_animations += "]}";
  }
  - json += "\"bufferViews\":[";
  - json += json_buffer_views;
  - json += "],\"accessors\":[";
  - json += json_accessors;
  - json += "],\"images\":[";
  - json += json_images;
  - json += "],\"textures\":[";
  - json += json_textures;
  - json += "],\"materials\":[";
  - json += json_materials;
  - json += "],\"meshes\":[";
  - json += json_meshes;
  - json += "],\"skins\":[";
  - json += json_skins;
  - json += "],\"animations\":[";
  - json += json_animations;
  - json += "],\"nodes\":[";
  - json += json_nodes;
  - json += "],\"scenes\":[";
  - json += "{\"nodes\":[";
  - json += json_roots;
  - json += "]}";
  - json += "],\"scene\":0";
  - json += ",\"asset\":{\"version\":\"2.0\", \"generator\":\"gltfpack\"}";
  + json += "\"asset\":{\"version\":\"2.0\", \"generator\":\"gltfpack\"}";
  json += ",\"extensionsUsed\":[";
  json += "\"KHR_quantized_geometry\"";
  if (settings.compress)
  @@ -2002,6 +1979,65 @@ bool process(Scene& scene, const Settings& settings, std::string& json, std::str
  }
  json += "]";
  + if (!json_buffer_views.empty())
  + {
  + json += ",\"bufferViews\":[";
  + json += json_buffer_views;
  + json += "]";
  + }
  + if (!json_accessors.empty())
  + {
  + json += ",\"accessors\":[";
  + json += json_accessors;
  + json += "]";
  + }
  + if (!json_images.empty())
  + {
  + json += ",\"images\":[";
  + json += json_images;
  + json += "]";
  + }
  + if (!json_textures.empty())
  + {
  + json += ",\"textures\":[";
  + json += json_textures;
  + json += "]";
  + }
  + if (!json_materials.empty())
  + {
  + json += ",\"materials\":[";
  + json += json_materials;
  + json += "]";
  + }
  + if (!json_meshes.empty())
  + {
  + json += ",\"meshes\":[";
  + json += json_meshes;
  + json += "]";
  + }
  + if (!json_skins.empty())
  + {
  + json += ",\"skins\":[";
  + json += json_skins;
  + json += "]";
  + }
  + if (!json_animations.empty())
  + {
  + json += ",\"animations\":[";
  + json += json_animations;
  + json += "]";
  + }
  + if (!json_roots.empty())
  + {
  + json += ",\"nodes\":[";
  + json += json_nodes;
  + json += "],\"scenes\":[";
  + json += "{\"nodes\":[";
  + json += json_roots;
  + json += "]}";
  + json += "],\"scene\":0";
  + }
  +
  if (settings.verbose)
  {
  printf("output: %d nodes, %d meshes\n", int(node_offset), int(mesh_offset));
  