A city cop -- and niece of former Met Shawon Dunston -- was released on $1,000 bail this morning after being charged with shooting her lesbian lover in a vicious quarrel. Ekeythia Dunston, 32, claimed she shot her long-time gal pal Erica Legall, 42, early Monday morning in self-defense because she was being attacked herself with a clothing iron. "Obviously there are extenuating circumstances here," said defense attorney Edgar De Leon in Manhattan criminal court. The couple -- who been together for five years and are raising two sons together -- began arguing over a text message Dunston received around...