Option search: 'opt:yes' always checks for any entry.

This means you cannot search for a selector/radio option whose
name is 'yes'. Oh well.
Add "has:" search.

"has:final" searches for final-copy-uploaded. "has:OPTION" means
"OPTION:yes". "has:paper" means some submission uploaded.
PaperColumn::register never HAD a second argument!
Add sort:timestamp and show:timestamp searches.

But keep them secret.