Ready for Oscar-worthy performances by British actors playing mathematical geniuses facing daunting personal odds? If that sounds overly specific, consider this: A few weeks ago, we had “The Theory of Everything,” starring Eddie Redmayne as the brilliant physicist Stephen Hawking. And now we have Benedict Cumberbatch in “The Imitation Game” as Alan Turing, the man chiefly responsible for cracking the vaunted Enigma code used by the Germans in World War II. But even though Turing literally …