Though theoretically pleasant, small talk—opening gambits, friendly chitchat, weather observations—tends to be the Rodney Dangerfield of conversation: it gets no respect. But the comedian Colin Quinn, raspy-voiced, Brooklyn-accented, and rat-a-tat loquacious, revels in it, including in his new solo theatre show, “Small Talk,” at the Lucille Lortel. A few weeks ago, after a preparatory standup set, Quinn, sixty-three and currently bearded, sat at a table in the bustling upstairs bar at the Comedy Cellar, in Greenwich Village, enjoying live music and a Diet Coke, occasionally chatting with passersby. “One of the things I’m saying in the show is that people adapt their personality to the times, for survival,” he said. In the social-media age, “the extremists set the tone,” but small talk, done right, can help. The live music got…