Also, separate catalogue search checkbox into a checkbox for each individual catalogue. Don't refer to catalogues jargon at all.

Old 4.3 code attached for a fork we had. Would need a lot of reworking.

This came back onto my horizon recently, as I realized that relevance-based searching will do a poor job aggregating different result kinds. It is possible we can extract an explicit relevance value from MySQL and compare that of different queries. But even if we do that, we can't do it when integrating external search systems or our own filesystem-based searching.