Procter & Gamble yesterday announced several changes in its Boston-based Gillette blades and razors operations, moves that will result in the closing of its Devens packaging plant in 2010. The closure will result in the loss of 350 local manufacturing jobs, with some 50 to 60 others being moved to another plant. Many of the Devens workers affected by the moves are employed not by Procter & Gamble, but by Sonoco Products, a worldwide maker of industrial and consumer packaging …