The fact that Alex Lehmann’s “Paddleton'‘ concerns two friends, one of which has just been told he’s dying of cancer, could make you run scared from the sob-fest that is about to happen, but “Paddleton” isn’t a “Love Story” or a “Terms of Endearment,” rather it’s a film that is incredibly light on its feet with humor and heartbreak and which sidesteps whatever cliches can be found in this kind of gooey territory. Despite some narrative straining, the payoff is beautifully rendered.