Method get_duration

uno/tools/Timer.cpp:13–15

   }

   double Timer::get_duration() const {
      return static_cast<double>(std::clock() - this->start_time) / static_cast<double>(CLOCKS_PER_SEC);
   }

   char* Timer::get_current_date() {
      const auto current_time = std::chrono::system_clock::now();