Mastervoices, a 100-plus member chorus (originally founded by Robert Shaw in 1941), gave a concert on Friday night in Alice Tully Hall that seemed tailored to provide respite and consolation following what can only be described as an exasperating week in the "real world." It was a joyous evening, both because of the sheer number of performers onstage using their voices to lift all of us up, and through careful, thoughtful programming, and creative ingenuity.