Jazz purists have slung more than a few arrows at Ramsey Lewis over the years, using phrases like “vulgar commercial intent” and “all the backbone of a jellyfish” to describe the Chicago-born pianist’s take on America’s greatest musical invention.   While critics acknowledge his brilliant technique, they have also roasted him for his flirtations with pop music, smooth jazz and electric piano over the past 51 years.  Lewis, for his part, is no apologist – nor should he be.He’s brought jazz to the masses over the past half-century as a radio host, PBS documentarian and artistic director at the Ravinia outdoor venue in suburban Chicago.  As he wrote in the Wall Street Journal recently, audiences should leave a jazz performance “feeling inspired and moved in some emotional way and not like they have just witnessed a class in advanced music theory or a garage jam session.”He’s touring in support of a just-released record, Songs from the Heart: Ramsey Plays Ramsey, with his trio, which plays aneminently listenable style of jazz that incorporates blues, gospel, swing and pop.  He’s joined on the bill in East Lansing by the vocalist Ann Hampton Calloway, a self-proclaimed diva who wraps her velvety alto around jazz, cabaret and the Great American songbook, though she is perhaps best known for writing the soundtrack to the TV show, The Nanny.   Commercial can be delicious.