Martin Scorsese’s “After Hours” is a comedy, according to the strict definition of that word: It ends hapily, and there are indications along the way that we’re not supposed to take it seriously. It is, however, the tensest comedy I can , building its nightmare situation step by insidious step until our laughter is hollow, or defensive. This is the work of a master filmmaker who controls his effects so skillfully that I was drained by this film – so…