Former German chancellor Angela Merkel is celebrating her 70th birthday on Wednesday with those closest to her, according to her spokeswoman. German politicians have already offered their congratulations and paid tribute to Merkel, who stood at the helm of Europe’s largest economy for 16 years. She was the first woman to hold that job. German President Frank-Walter Steinmeier honoured Merkel as a “role model and a hallmark of our democracy” ahead of her birthday. Merkel had decisively shaped the path of a united Germany as chancellor, he said. Former German chancellor Gerhard Schröder, whom Me…