By Denny Dyroff, Entertainment Editor, The Times This weekend has a trifecta of events which are traditionally party time events – Cinco de Mayo, the Kentucky Derby and Winterthur Point-to-Point. There will be a bustle of activity this weekend on Kennett Pike just a few miles south of Kennett Square at Winterthur (Route 52, Wilmington, Delaware, 302-888-4600,www.winterthur.org) with the staging of...