A controversial production of Idomeneo in Berlin went off with little incident Monday. A powerful male voice called out “stop it!” and “boo!” as the heads of Islam’s founder, along with those of Jesus, Buddha and Poseidon, the Greek god of the seas, came tumbling out of a sack hefted by Idomeneo. But several voices from the other side of the hall yelled, “continue, continue,” their cheers clashing with the voice of the critic, and the cast and orchestra received prolonged applause.”