FULLTEXT: Num cols returned on hit should be switch-selectable

Maybe this will be construed as a Task per policy, but it's at least a human-factors Bug, if it now works the way intended.

Currently a hit on even 1 column in a multi-column search returns all columns. That should be a per-call switch (RETURN_ALL_COLS, RETURN_COLS_HIT_ONLY)...or, slightly more succinctly, ON_HIT_RETURN_HIT, ON_HIT_RETURN_ALL_COLS).

Returning only the column(s) hit reduces or eliminates the need for post-hoc filtering when it's not known in advance which column has which search target in a given record and the columns not hit are not important.