Richard Scheinin has a great time at this year’s San Jose Jazz Festival. But he entertains a nagging question: “Was the ‘Jazz’ in the title of the festival starting to take a back seat to funk, pop, soul? And looking ahead, is San Jose’s jazz festival about to morph into one more ‘jazz and pop’ festival, in which jazz is a guest at its own party? Why does it matter? Because there are a million venues for the Nevilles and Dr. John, who closed Saturday’s Main Stage events. There are, on the other hand, very few venues, a shrinking few, for jazz, which is continually pushed to the margins…”