ALIGOFactory add_BS function uses parameter file and default 45 deg AOI

This modifies the add_BS function to use parameters from the parameter file. Previously a 50/50 lossless beamsplitter was hardcoded with a 0 deg AOI. That was changed to 45 deg by default. The BS AR surfaces were also changed from mirrors to beamsplitters with symbolic links to the AOI of the HR surface. And finally support for non-zero AR surface reflectivity was added, but the 50 ppm AR reflectivity from the original kat files was not added to the lho_O4 parameter file.