An armed robbery on Madison's West Side Thursday night.  Police say two teenage girls were leaving a soccer game at Memorial High School on Gammon Road when a suspect got out of a car, pointed a gun at one of the girls and demanded the keys to their Range Rover.    No shots were fired and no one was hurt.  The vehicle was found about five hours later, crashed at Windom way and Elka Lane on the north side.  No arrests have been made.