GOD, it's hot! I'm sitting here knocking down a container of iced coffee (America's most controversial and worst prepared summer drink) while trying to jell a few coherent thoughts on last Saturday's jazz concert. It isn't easy, and the heat isn't the only reason this is so. Every time I get myself involved in a thing of this sort, I come away with a montage of impressions that range all the way from brief film-clips of hordes of the backstage hangers-on who seem to infest all jazz shows being for once tossed out on their duffs, to herds of grandstanding photographers who likewise show up at all these affairs and who seem to think jazz was created to be a subject for low-key black-and-whites...