Two of public radio’s most widely listened-to classical music programs are jumping halfway across the country. “Performance Today” and “SymphonyCast” have been dumped by the increasingly news-oriented National Public Radio, and will soon begin being produced by American Public Media, the national distribution arm of Minnesota Public Radio, which also distributes “A Prairie Home Companion,” “Marketplace,” and many other widely heard programs. “Performance Today” has been dropped by a number of stations over the last few years as classical music has become a tough sell with local stations.