Ok. that makes sense. i think i can do without special cases and make the whole cores files attiny85 only. I get the feeling that the #if defined is only needed to make one cores dir for a few very similar AVR's. maybe later someone can add the special cases for a attiny84.
I was incorporating the latest developements into the first post but i'm a little ambivalent about it. of course it is nice to have the latest version available, but it could happen that someones comment becomes obsolete. that is confusing at the least...
i will not do that again.