By Denny Dyroff, Entertainment Editor, The Times Deb Callahan Up until about a week ago, the Sellersville Theater (24 West Temple Avenue, Sellersville, 215-257-5808, www.st94.com) was holding down the fort in the battle to keep indoor performances with live audiences featuring national acts on the local schedule The venue was able to present live music and comedy at 10% occupancy to live performances...