message: gltfpack: Always fill fallback buffer
  Even though the fallback buffer is not always used, it is easier to
  always fill it with data because that way we can write sensible offsets
  and byte length into the JSON blob and just omit the actual file.
  This requires more memory but simplifies the code flow.
diff: @@ -2913,7 +2913,7 @@ void writeLight(std::string& json, const cgltf_light& light)
  append(json, "}");
  }
  -void finalizeBufferViews(std::string& json, std::vector<BufferView>& views, std::string& bin, std::string& fallback, const Settings& settings)
  +void finalizeBufferViews(std::string& json, std::vector<BufferView>& views, std::string& bin, std::string& fallback)
  {
  for (size_t i = 0; i < views.size(); ++i)
  {
  @@ -2939,11 +2939,8 @@ void finalizeBufferViews(std::string& json, std::vector<BufferView>& views, std:
  compression = 0;
  }
  - if (settings.fallback)
  - {
  fallback += view.data;
  }
  - }
  else
  {
  bin += view.data;
  @@ -3423,7 +3420,7 @@ void process(cgltf_data* data, std::vector<Mesh>& meshes, const Settings& settin
  if (!views.empty())
  {
  std::string json_views;
  - finalizeBufferViews(json_views, views, bin, fallback, settings);
  + finalizeBufferViews(json_views, views, bin, fallback);
  append(json, ",\"bufferViews\":[");
  append(json, json_views);
  