Rebuild Search Results After liszt:updated

@kenearley @stof @koenpunt @elkelk

This is a slight modification of #947 which adds a call to `winnow_results` after triggering a `liszt:updated`. This is useful for people who are modifying the contents of the underlying select while mid-search (think ajaxy). I've added a conditional that ensures it only happens when results are showing.

I believe this fixes things like #1221 and #510.