Polarization angle swings in blazars: The case of 3C 279

International Max Planck Research School (IMPRS) for Astronomy and Astrophysics at the Max Planck Institute for Radio Astronomy; Universities of Bonn and Cologne; Academy of Finland project [274477]; NASA Fermi GI grant [NNX11AQ03G]; Russian Foundation for Basic Research [13-02-12103, 14-02-31789]; RFBR [12-02-01237a]; UNAM DGAPA-PAPIIT [IN116211-3]; Ramon y Cajal grant of the Spanish Ministry of Economy and Competitiveness (MINECO); Spanish Ministry of Economy and Competitiveness (Spain); Regional Government of Andalucia (Spain) [AYA2010-14844, AYA2013-40825-P, P09-FQM-4784]; Fermi Guest Investigator [NNX08AW56G, NNX09AU10G, NNX12AO93G, NNX14AQ58G]; Russian RFBR [15-02-00949]; St. Petersburg University research [6.38.335.2015]; Shota Rustaveli National Science Foundation [FR/638/6-320/12, 31/77]