PSGML patch bugfix

Just bugfixed the PSGML explicit fixed attribute patch. Attribute edit mode didn’t insert fixed attributes properly. I think I should also take this time to mention that I haven’t tested this patch very much, so it quite likely breaks down pretty easily. Furthermore, if this screw up your computer, files, data, marriage, or thread in space-time I’m totally not responsible. (Just ask anyone.) Further furthermore, this is not at all an official patch, since I’m sure the people that wrote PSGML could do a better job at this than me; if there are any problems, please report them to me, not to the PSGML folks.