Relicensing from Apache License v2 to GPLv3+. This is only done on classes that (have copyright by Dominik Schürmann or Markus Doits) or (are completly refactored by me and contain no remaining code by Thialfihar). Code by Thialfihar (not reachable by mail) and Shaun Senecal (disagreed on license change) remain Apache License v2.