Sorry but it took a while before I wrote the pieces of code
concerning slot inheritance. Inbetween I start to use ede and I
am very happy with it now !
First I think that I am not allowed to commit my changes to the
cvs repository for the eieio project. Hence I simply join the
modified eieio.el file.
Modifications are between line 733 and 776.
I ran the tests and they passed. Moreover I going to use
intensively the eieio package, hence if there is a bug
somewhere in the code I wrote, I'll certainly discover it soon