Option to auto-position the suggestions even when not appended to the body

I think this is pretty useful and the implementation isn't too complex. It would address #144, which I know has been closed, but certainly would have been useful to me. I hope you might find it similarly valuable.

By default, this maintains the current behavior, where auto-positioning of the suggestions is only done if the suggestions are appended to the document body. However, if you pass `autoPosition: true` in the options, this will auto-position the suggestions no matter where they are in the DOM.