Show large single combo when clicking the item in bulk list

[ArtofBugs]

For #691 - when the single combo item in the bulk list is clicked, it opens the large single combo display (by setting the selected right list emoji); clicking the large single combo takes you back to the bulk list (by deselecting the right list emoji).

[ArtofBugs]

I wanted to get the bulk list to scroll to the single item just after the large single combo display is closed, but it's proving to be a bit more difficult than I thought (I have refs for all the items in the bulk list, but how do I pick the one with the matching left and right emojis?), I think PR #474 will probably be helpful, but I might leave the scrolling stuff out for now for this PR (it seems in the current production site, bulk list scrolling is also reset when a right emoji is selected and then deselected). In the meantime, all the basic functionality I listed in the issue seem to be working on my end. :)