If you’re a musician in New Orleans, you’re never far from the source. In the case of trumpeter/vocalist Mervin “Kid Merv” Campbell, he’s got it coming and going. His great uncle, Kid Rena, was a local star during the infancy of jazz in the early 20th Century, a rival of Louis Armstrong’s who replaced Satchmo in Kid Ory’s band in 1919. But Merv also is close to the source ...