Add scroll buttons

Problems with this merge request

Adding new questions

There's a visual bug that occurs when adding questions, you see the following:

Note that in the screenshot, multiple questions were added

I couldn't find out why this was happening, so as a hacky fix, I added a statement to scroll the container to the start the first time questions are added.

Overspill calculation

I couldn't find a reliable way of calculating whether or not the slider was overscrolling. For the time being I've just added the buttons when there's at least one question in the list

Closes #351 (closed)