Moving In At University: University sophomore Lynn Bravilman of Gary, Ind. gets an assist from Steve Mash of Detroit yesterday as she moves into South Quadrangle in preparation for start of classes Monday at the U-M. The two are among a record number of about 31,000 students who began registering yesterday, when the bulk of them arrived in the city. Many came in cars loaded with belongings, causing what police indicate was one of the worst downtown traffic jams in the history of the city. Some officers performed traffic duty daylong at dormitories as the moving operations grew.