Describe your changes

With this PR, user have chance to check whether key press event is repeat.

auto onKeyPressed = [this](ax::EventKeyboard::KeyCode code, ax::Event* e) -> void {
  if(!static_cast<EventKeyboard*>(e)->isRepeat()) {
      // one shot
  }
  else { 
      // repeat shot
  }
}

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Axmol 3.x ------------------------------------------------------------

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