By Caldwell Titcomb March 2: The Contemporary Music Ensemble in residence at Boston University, Alea III, under the direction of Theodore Antoniou, offers a free concert in celebration of the late eminent composer/teacher/conductor Lukas Foss (1922–2009). Works by Foss to be performed are “Echoi,” “For Toru,” “Elegy for Anne Frank,” “For Aaron,” “The Prairie,” and…