Function unescape

dependencies/json/json.hpp:12444–12448

unescape "~1" to tilde and "~0" to slash (order is important!)

    /// unescape "~1" to tilde and "~0" to slash (order is important!)
    static void unescape(std::string& s)
    {
        replace_substring(s, "~1", "/");
        replace_substring(s, "~0", "~");
    }

  private:
    /*!