It’s difficult to think of a better way to bid farewell to a New York summer than with Lincoln Center’s “Mostly Mozart” festival, and seeing Mark Morris Dance Group performing Mozart Dances was the icing on the cake. From the sound of them, you’d never know the three works Morris chose were written in the last decade of the composer’s short life. Performed by Garrick Ohlsson with the Mostly Mozart Festival Orchestra under the baton of Louis Langrée, Mozart’s piano concertos (11 and 23) and double piano sonata (Ohlsson was joined by pianist Inon Barnatan) collectively sounded light, sprightly and enchantingly melodic on Wednesday night’s performance.