MAGDEBURG, Germany, July 29 (Reuters) - Thousands took to the streets to protest against the far-right Alternative for Germany (AfD) on Friday and Saturday as the party held a convention to choose its candidates for European parliamentary elections next year. Protesters outside the conference venue in the city of Magdeburg waved banners with messages like "stand together against right-wing hate" or "Nazis out". Polling at 22% behind the opposition conservatives, the AfD denies it is a Nazi party. Analysts say it is tapping into voters' fears about recession, migration and the green transition. The AfD last month won a vote...