SAM ZELL called himself “the Grave Dancer”, even though, as he explained, his penchant for buying distressed assets “wasn’t so much dancing on graves as …raising the dead”. In the mid-1970s, when he coined this nickname, America’s property market was struggling. Mr Zell, who died on May 18th at the age of 81 and with a fortune of more than $5bn, had already made good money erecting and managing apartment buildings in small but…