BERLIN (Reuters) - The Ifo institute on Tuesday cut its 2020 growth forecast for the German economy to 1.7% from 1.8% previously as a manufacturing recession spills over into other sectors of Europe's biggest economy."There is a diverging economic development: the export-oriented manufacturing sector, which accounts for about a quarter of economic output, is in recession," Ifo economist Timo Wollmershaeuser said.At the same time, domestic service providers and the construction industry are..