Filter rays

It could be useful to filter a list of rays to remove those which are outside the SWS window. This change introduces a new function (SiS_filter_Rays_SWSwindow) which takes a list of rays as input and removes any that are two horizontal to allow SWS analysis before returning the trimmed list. I also add the angles, source and receiver locations to the rays generated by SiS_create_VRays.