Boston’s own Margo Thunder, above, headlined the Franklin Park Coalition’s second annual Jazz and R&B Festival last Saturday (Sept. 17). The lineup included Fred Woodard, Wali Ali, and Mike Rollins. Angie Dickerson, aka Mz. Rhythm, and the Boston Rhythm Riders, led the audience in hugely popular line dances. The R&B got serious with Midnight Crew’s All-Star Review featuring