Exported IOR

Blender doesn't have a "extIOR", or rather the IOR of empty space is just 1.0. Wienori, assumes an "air" IOR of 1.000277. So when exporting and importing from blender we have to convert the IOR values. The importer does this as blender_ior = intIOR / extIOR but the exporter doesn't do the inverse conversion and just uses the blender IOR value directly as intIOR. I am quite sure this is wrong.