Sam Rivers Trio and NEC Jazz Orchestra New Music Now series Institute for Contemporary Art South Boston, 7:30 p.m. $25/$20 It's almost perverse to include an 84-year-old man in a series called New Music Now, but Sam Rivers isn't your average octogenarian. The reedsman, who has played jazz since the 1950s, is a living repository of free jazz, a performer whose recordings over the past two decades have become essential listening for those interested in...