[sqlite] FTS5 rank configuration option

[chromedou...@yahoo.com]

The documentation says that a persistent rank can be set with
INSERT INTO ft(ft, rank) VALUES('rank', 'bm25(10.0, 5.0)');
However, I can only get it to work on the same database connection as the 
query. Subsequent database connections seem to use the standard default 
ranking. Is this by design?