Add detecor frame sky-parametrization
It's convenient to sample in this parametrization of the sky-coordinates
This is implemented in LALInference
in https://git.ligo.org/lscsoft/lalsuite/blob/master/lalinference/src/DetectorFixedSkyCoords.c
It's convenient to sample in this parametrization of the sky-coordinates
This is implemented in LALInference
in https://git.ligo.org/lscsoft/lalsuite/blob/master/lalinference/src/DetectorFixedSkyCoords.c