After a pressure-packed year of putting on classical performances in the midst of a pandemic, and facing festering tensions over his treatment of actors and staff, Ethan McSweeny has resigned as artistic director of American Shakespeare Center, the Staunton, Va., company announced Friday. Rodney Young, chairman of the 20-member board of trustees, told the Washington Post that mediators were brought in from 91¶ÌÊÓÆµ to aid in improving trust and communications after the split.