German President Frank-Walter Steinmeier starts his three-day official visit to Turkey on Monday, where he plans to meet opposition leader and Istanbul Mayor Ekrem İmamoğlu, before he meets President Recep Tayyip Erdoğan on Wednesday in Ankara. İmamoğlu, who has just been confirmed in office, is seen as the hope of the opposition and a possible future presidential candidate. Steinmeier is set to meet him shortly after arriving in Istanbul on Monday. During his visit, Steinmeier plans to honour the achievements of the many Turks who have come to Germany since the 1960s as so-called guest worker…