Talk about fusion!  For “Hands Down,” the opening cut of his 1979 album Relight My Fire, Dan Hartman enlisted rock and roll great Edgar Winter to weave his alto saxophone licks throughout the Latin-flavored disco track, and Stevie Wonder to provide his instantly recognizable harmonica.  Hartman wasn’t just a dilettante, but a regular musical renaissance man.   A veteran of the Johnny Winter Band and the Edgar Winter Group, he wrote the latter’s smash hit “Free Ride,” and successfully completed the transition to solo stardom with 1978’s “Instant Replay,” a No. 1 Disco…