Fix headers, copyright notices, and doxygen tags

src/account.cpp

src/accountcreator.cpp

src/accountcreator.h

src/audio/audiofile.cpp

src/audio/audiofile.h

src/audio/audiortp.cpp

src/audio/audiortp.h

src/audio/codecDescriptor.cpp

src/audio/codecDescriptor.h

src/audio/common.h

src/audio/dtmfgenerator.cpp

src/audio/ringbuffer.h

src/config/config.cpp

src/config/config.h

src/dbus/callmanager.cpp

src/dbus/configurationmanager.h

src/iaxaccount.cpp

src/iaxaccount.h

src/iaxcall.cpp

src/iaxcall.h