Support inverted display of suggestions

[danwild]

Nice plugin thanks 👍

This PR adds optional params:

• parentElementId {String} - to specify the parent div to append autocomplete (defaults to body)
• invertScroll {Boolean} - to ensure suggestions at the bottom of the list are scrolled into view first

The addition of these options allows us to use this plugin for inverted display of suggestions.
Why? If you try and use this in a footer it doesn't work so well - because there is no room to display the suggestions below.

Here's how it works now, with inverted options (and some css tweaks):

[michael-ts]

I'm not sure if I'm using this wrong, but I can't get it to work.
First of all, I had to define an element with an id "body". Not sure why this was necessary, as I had the stock version working without it. Somehow related to parentElementId?

Second, it still displays the dropdown below the input. My element is far enough from the bottom that I can still see the dropdown, but as it is about 75% down I would prefer to get the behavior shown above.