It has been a particularly heavy season at Opera Theatre of St. Louis, with an absolutely splendid run of Marc Blitzstein’s “Regina” and the emotionally-charged world premiere of Huang Ruo’s “An American Soldier.” It was thus welcome that the final production to debut this season, Gluck’s “Orfeo and Euridice,” provided an uplifting ending. This production by director Ron Daniels, though {…}