don’t finish query without results too early
always fix progress bar width before displaying it

This fixes a race where the backend would respond with progress update
messages (from cache) before the DOM was first fully rendered, and hence
before the window.load was executed (I think).
properly disable “group by package” checkbox for single-package results
s.done will be set in addEvent when adding the zero-sized event
stop obsoleting events once the query is done
set progress bar to finished, even when 0 files are grepped
garbage collect query state entries, limit to 10 for now
display fatal errors only once, in the progress bar (Thanks Mark)
pagination: fix ellipsis, place prev/next arrows outside (Thanks Mark)