For years I’ve considered the term “performance artist” a buzzword for a performer who gets up on a stage and does something vaguely like music, vaguely like theater, but doesn’t really do much of anything (Laurie Anderson, anybody?). Contrastingly, there’s Dr. Lonnie Smith, appearing through Sunday at Dizzy’s Club Coca-Cola in a quartet with the outstanding saxophonist David “Fathead” Newman. Dr. Smith is not only one of the all-time masters of the Hammond B-3 organ, but is an extravagant visual performer as well.