message: fixed compile error in Ref
diff: @@ -117,17 +117,17 @@ namespace oidn {
  ptr = nullptr;
  return res;
  }
  - };
  - template<typename T> __forceinline bool operator < (const Ref<T>& a, const Ref<T>& b) noexcept { return a.ptr < b.ptr; }
  + friend __forceinline bool operator < (const Ref<T>& a, const Ref<T>& b) noexcept { return a.ptr < b.ptr; }
  - template<typename T> __forceinline bool operator ==(const Ref<T>& a, std::nullptr_t) noexcept { return a.ptr == nullptr; }
  - template<typename T> __forceinline bool operator ==(std::nullptr_t, const Ref<T>& b) noexcept { return nullptr == b.ptr; }
  - template<typename T> __forceinline bool operator ==(const Ref<T>& a, const Ref<T>& b) noexcept { return a.ptr == b.ptr; }
  + friend __forceinline bool operator ==(const Ref<T>& a, std::nullptr_t) noexcept { return a.ptr == nullptr; }
  + friend __forceinline bool operator ==(std::nullptr_t, const Ref<T>& b) noexcept { return nullptr == b.ptr; }
  + friend __forceinline bool operator ==(const Ref<T>& a, const Ref<T>& b) noexcept { return a.ptr == b.ptr; }
  - template<typename T> __forceinline bool operator !=(const Ref<T>& a, std::nullptr_t) noexcept { return a.ptr != nullptr; }
  - template<typename T> __forceinline bool operator !=(std::nullptr_t, const Ref<T>& b) noexcept { return nullptr != b.ptr; }
  - template<typename T> __forceinline bool operator !=(const Ref<T>& a, const Ref<T>& b) noexcept { return a.ptr != b.ptr; }
  + friend __forceinline bool operator !=(const Ref<T>& a, std::nullptr_t) noexcept { return a.ptr != nullptr; }
  + friend __forceinline bool operator !=(std::nullptr_t, const Ref<T>& b) noexcept { return nullptr != b.ptr; }
  + friend __forceinline bool operator !=(const Ref<T>& a, const Ref<T>& b) noexcept { return a.ptr != b.ptr; }
  + };
  template<typename T, typename... Args>
  __forceinline Ref<T> makeRef(Args&&... args)
  