By Daren Butler ISTANBUL, June 4 (Reuters) - Days of anti-government protest in Turkey have achieved one feat that has eluded the authorities for years: uniting the fiercely rival and sometimes violent supporters of Istanbul's "Big Three" football clubs. Besiktas, Galatasaray and Fenerbahce fans have come together in new-found solidarity during five days of demonstrations against Prime Minister Tayyip Erdogan's government. ... More...