When Mark Murphy died in October 2015, some of the obituaries mourned the passing of the greatest jazz singer in history. Murphy was the last of his kind, a hipster of the Kerouac generation, who rejected the straight life of prosperity and numb consumerism. With a catalogue of more than 40 albums under his own name as well as numerous guest appearances, Mark Murphy was a consummate improviser, who never sang a song the same way twice. He could have...