Continuity is the watchword for Lansdale officials.   Borough council held a reorganization meeting Tuesday night and reelected Council President Matt West as well as Council Vice President Paul Clemente.   The vote for West was unanimous.   Incumbent council members Rich DiGregorio and Jack Hansen as well as newcomers Denton Burnell and Steve Malagari were sworn-in.   They all won election last November.   Mayor Andy Szekely administered the oath of office.   With the swearing-in of Burnell, DiGregorio, Hansen and Malagari, democrats now hold a six-to-three margin on council.