* #6104: AudioCodec moved to sfl namespace

sflphone-common/src/audio/codecs/alaw.cpp

sflphone-common/src/audio/codecs/audiocodec.cpp

sflphone-common/src/audio/codecs/audiocodec.h

sflphone-common/src/audio/codecs/audiocodecfactory.cpp

sflphone-common/src/audio/codecs/celtcodec.cpp

sflphone-common/src/audio/codecs/g722.cpp

sflphone-common/src/audio/codecs/gsmcodec.cpp

sflphone-common/src/audio/codecs/speexcodec_nb.cpp

sflphone-common/src/audio/codecs/speexcodec_ub.cpp

sflphone-common/src/audio/codecs/speexcodec_wb.cpp

sflphone-common/src/audio/codecs/ulaw.cpp

sflphone-common/src/audio/sound/audiofile.cpp

sflphone-common/src/audio/sound/audiofile.h

sflphone-common/src/iax/iaxvoiplink.cpp

sflphone-common/src/managerimpl.cpp

sflphone-common/src/sip/sdp.cpp

sflphone-common/src/sip/sdp.h

sflphone-common/src/sip/sipvoiplink.cpp