driver/audiodec: implement AAC support (via FFMPEG, with some rough edges)
driver/audiodec/ffmpegdec: reopen codec on error (experimental fix)
driver/audiodec/ffmpegdec: minor cleanup
driver/audiodec: Switch to ffmpeg, drop custom decoder implementations, drop libvorbis/libmad/libid3/libogg/libflac. Not fully regression tested.

Conflicts:
	configure.ac
	src/Makefile.am
	src/driver/audiodec/Makefile.am
driver/audiodec: metadata fix
audiodec/ffmpegdec: convert id3 tags to UTF8
driver/audiodec: don't encode utf8 to utf8
drop #ifdef ENABLE_FLAC
audioplayer, ffmpegdec: embedded cover support

Conflicts:
	src/gui/audioplayer.cpp
driver/audiodec/ffmpegdec: don't set cover-art variable on failure
driver/audiodec/ffmpegdec: cover fix
driver/audiodec,audiometadata: cover file handling fixed
driver/audiodec/ffmpegdec.cpp, driver/audiometadata.cpp: fix compile
driver/audiodec/ffmpegdec.cpp: fix bits per sample, fix av_free_packet
driver/audiodec/ffmpegdec.cpp: fix ogg; get metadata also from streams,
ie some ogg dont have global metadata
driver/netfile.cpp: fix warning
driver/audiodec/ffmpegdec.cpp: parse metadata only for AVMEDIA_TYPE_AUDIO streams;
fix type_info and possible crash (thanks Jacek)
driver/file.cpp: add AAC file type, add .dts extension
gui/audioplayer.cpp: add AAC file type, save last used directory
gui/filebrowser.cpp: add AAC file type