add option for slide autostop when next, prev etc are pressed

Add autoStopWhenControlled option, default is set to true. When the slider is set to auto, it will be stopped automatically when next, prev or the pager dots are clicked.
```
var clickNextBind = function(e){
       // if auto show is running, stop it
      if (slider.settings.auto) el.stopAuto();
      ...
}
```
This pull request add an option `autoStopWhenControlled` to prevent it if it's set to false. That means, if `autoStopWhenControlled` is set to false, the slides will not stop when next, prev or the pager dots are clicked.