Add Carl Hetherington to AUTHORS file.
Add Carl Hetherington to AUTHORS file.

adiknoth/calf,jnetterf/calf,adiknoth/calf,jnetterf/calf,zamaudio/calf-LR4,zamaudio/calf-LR4,jnetterf/calf,zamaudio/calf-LR4,adiknoth/calf,adiknoth/calf,zamaudio/calf-LR4,zamaudio/calf-LR4,adiknoth/calf,jnetterf/calf,jnetterf/calf