CBS and the folks responsible for these vintage TV restorations have done such a great job with computer-colorizing old episodes that, even as TV critic purist, I find it impossible to complain. And these annual showings around the holidays have become a new CBS tradition, one which I happily endorse. Tonight’s two episodes of I Love Lucy this year, presented in living color, are “The Christmas Episode,” which has been shown every year on this new prime-time showcase, and “Pioneer Women,” a battle of the sexes in which Lucy and Ethel endeavor to churn their own butter and, even more disastrously, bake their own bread.