sqeeze in a minor bugfix. I wouln't be surprised it is too late, but since it really is sort of minor, it doesn't matter really. I had mistakenly put the export of dispersion and absorption parameters in the ray_mirror block instead of ray_transp, which means that both dispersion and absorption can only be used if both ray mirror and ray transp are enabled. Anyway, I don't want to make everyone recompile release builds if already done, it is minor, but users should take this into account at least.