Staunch Allies, Tested by Adversity McCain Relies on a Cadre of Fellow POWs to Help Get Message Across By John Wagner and Anita Kumar Washington Post Staff Writers Wednesday, September 3, 2008; Page A24 ST. PAUL, Minn., Sept. 2 -- When the roll call reaches Maryland on Wednesday night, a convention delegate with a special bond with John McCain is scheduled to step forward to announce the state's 37 votes. Everett Alvarez Jr. of Potomac was a prisoner of war with McCain in the same camp in North Vietnam, where they came to know each other during their final year...