message: gltfpack: Use 8-bit skinning weights
  Note: these onl work in Babylon.JS currently, Three.JS has a bug with
  skin weight normalization that breaks U8 weights.
diff: @@ -402,21 +402,18 @@ std::pair<std::pair<cgltf_component_type, cgltf_type>, size_t> writeVertexStream
  {
  const Attr& a = stream.data[i];
  - /*()
  - // TODO: normalize sum to 255
  uint8_t v[4] = {
  uint8_t(meshopt_quantizeUnorm(a.f[0], 8)),
  uint8_t(meshopt_quantizeUnorm(a.f[1], 8)),
  uint8_t(meshopt_quantizeUnorm(a.f[2], 8)),
  uint8_t(meshopt_quantizeUnorm(a.f[3], 8))};
  - */
  - float v[4] = { a.f[0], a.f[1], a.f[2], a.f[3] };
  + // TODO: normalize sum to exactly 255
  bin.append(reinterpret_cast<const char*>(v), sizeof(v));
  }
  - return std::make_pair(std::make_pair(cgltf_component_type_r_32f, cgltf_type_vec4), 16);
  + return std::make_pair(std::make_pair(cgltf_component_type_r_8u, cgltf_type_vec4), 4);
  }
  else if (stream.type == cgltf_attribute_type_joints)
  {
  