By Denny Dyroff, Entertainment Editor, The Times Chester County has several annual events with impressive longevity and one of them is scheduled for this weekend — the Chester County Old Fiddlers’ Picnic (Hibernia County Park, off Route 340, Wagontown, 610-383-2812, http://dsf.chesco.org/ccparks). The lively annual event, which is scheduled for August 10, is celebrating its 91st anniversary...