The Mets made their first trade of the offseason Friday, swapping disliked lefthanded relievers with the Yankees. Old and overworked Mike Stanton 32 is back in the Bronx, where he belongs, and battered ex-Yankee Felix Heredia comes to Shea. Few Mets fans ever warmed to Stanton, perhaps because they got tired of seeing him pitch nearly every day, and with a no-trade contract and a big salary, it’s a miracle the Mets got anything for him. Let’s hope Heredia can be used judiciously and effectively. Felix wore 45with the MFYs, and that number is technically available, but…