Thousands of residents of subsidized housing in New Jersey got a last-minute Christmas gift this week, after federal officials agreed to a complex arrangement that advances 21 housing authorities $80 million to renovate old buildings.The authorities will repay the money over 20 years, using 30 percent of their annual appropriation for capital maintenance from the U.S. Department of Housing and Urban Development. And they benefited from a joint borrowing operation overseen by the state."It's a good news story for housing authorities for once," said David Gardner, executive director of the Morristown Housing Authority, which helped organize the borrowing effort through...