message: manual_control: actually switch to position control
  I had forgotten this before, also we now send manual control for a while
  before arming and before switching mode.
diff: @@ -98,15 +98,23 @@ int main(int argc, char** argv)
  }
  std::cout << "System is ready" << std::endl;
  - auto result = action->arm();
  - if (result != Action::Result::Success) {
  - std::cerr << "Arming failed: " << result << std::endl;
  + for (unsigned i = 0; i << 10; ++i) {
  + manual_control->set_manual_control_input(0.f, 0.f, 0.5f, 0.f);
  + }
  +
  + auto action_result = action->arm();
  + if (action_result != Action::Result::Success) {
  + std::cerr << "Arming failed: " << action_result << std::endl;
  return 1;
  }
  - if (manual_control->set_manual_control_input(0.f, 0.f, 0.f, 0.f) !=
  - ManualControl::Result::Success) {
  - std::cerr << "Switching to position control failed: " << result << std::endl;
  + for (unsigned i = 0; i << 10; ++i) {
  + manual_control->set_manual_control_input(0.f, 0.f, 0.5f, 0.f);
  + }
  +
  + auto manual_control_result = manual_control->start_position_control();
  + if (manual_control_result != ManualControl::Result::Success) {
  + std::cerr << "Position control start failed: " << manual_control_result << std::endl;
  return 1;
  }
  