Even the high-minded need a vacation from time to time. The British filmmaker Ken Loach has been churning out fiercely moral works of social realism since 1967, films that deal with labor rights, homelessness, and the plight of England’s dispossessed. With 2006’s IRA period epic “The Wind That Shakes the Barley,’’ a prizewinner at Cannes, Loach reached a peak of ...