Re-license almost all the playback modules to LGPLv2.1+ with
authorization from their respective contributors (230+)

This includes:
 - access, codec, packetizers, demux
 - audio filters, audio mixers, audio output
 - video filters, video chroma, video output
 - text renderers
 - XML parser
 - ARM NEON and SSE2 optimisations (mostly for chromas and filters)

Some modules are not concerned:
 - BDA and DShow access modules because Manol Manolov is AWOL
 - Real RTSP, because it is derived from Xine
 - x264 and t140 because they are encoders only
 - DLL Loader, because it is derived from MPlayer
 - DTS packetizer, because Jon Lech Johansen is AWOL
 - Shine and WMAfixed, because they are derived from Rockbox
 - Real demuxer, as it is derived from MPlayer and Wang Bo is AWOL
 - MPC demuxer, as Yavor Doganov is AWOL
 - Tivo demuxer, because it is derived from an MPlayer fork
 - Playlist demuxer, (WPL and ZPL parts missing), because suheaven is AWOL
 - iOS audio output and video display, because author refuses the license change
 - Equalizer and compressor, because Ronald Wright is AWOL
 - Mono, Headphone and Dolby, because author refuses the license change
 - hqdn3d and yadif, because they are from MPlayer/libavfilter
 - remoteosd, because it derives from RealVNC code
 - MMX optimisations, because Ollie Lho, from SiS, is AWOL
 - Rotate, because it depends on GPL motion

Nota Bene:
 - Some modules depend on GPL-only libraries, a LGPL module does not mean
   that the resulting binary module will be LGPL.
   Libraries affected would include liba52, libdvdcss, libdvdnav, libdvdread,
   faad2, libdca, libmad, libmpeg2, libpostproc, SRC, sid, zvbi and probably others.