Oresteia ****
By: David ShewardLiuba Sokalova (Clytemnestra), Maria Litke (Cassandra)Sergey Taneyev's Oresteia is unfamiliar territory for the average operagoer. Rarely performed in its entirety since its 1895 premiere in Russia, the mammoth work is in its North American premiere, at Bard College's SummerScape Festival. Unlike many other Russian works of the same period, this opera's source material is Aeschylus's Greek trilogy on…