BERLIN (Reuters) - Former IMF head Horst Koehler has been elected Germany's ninth post-war president by a special federal assembly in a poll overshadowed by the inclusion of a Nazi-era judge who sentenced World War Two deserters to death. Koehler, who quit as managing director of the International Monetary Fund to run for the largely ceremonial office, won an absolute majority on Sunday with 604 votes in the 1,204-member assembly. Chancellor Gerhard Schroeder's candidate Gesine Schwan, who gained 589 votes, was defeated in what opposition conservatives hope will be a harbinger for the ousting of the SPD-Greens government in a...