Mets fans will start saying their good-byes to the city’s “other” baseball stadium today, as the final opening day game is played at Shea Stadium. Next year, the Mets will settle into their new ballpark, Citi Field. Citigroup is spending $400 million over 20 years for the park’s naming rights. Before today’s game, the Mets will pay tribute to William Shea, the man who got the stadium built 44 years ago. Meanwhile, City Councilman Hiram Monserrate will lead a protest outside the stadium against the proposed redevelopment of nearby Willets Point.