Clean up normalisation code, does not affect any computed values.
Clean up normalisation code, does not affect any computed values.

SheffieldML/forkedGPmat,SheffieldML/forkedGPmat,SheffieldML/forkedGPmat,lawrennd/GPmat,SheffieldML/forkedGPmat,SheffieldML/forkedGPmat,SheffieldML/forkedGPmat,lawrennd/GPmat,lawrennd/GPmat