By Denny Dyroff, Entertainment Editor, The Times There are times when fans head to a show to see one of their favorites as headliner and cringe if they have to sit through an opening act. When fans head to The Keswick Theater (291 N. Keswick Avenue, Glenside, 215-572-7650, www.keswicktheatre.com) on April 23 to attend Tesla’s “Shock … Continue reading On Stage: No need to ‘Cringe’ at this act