fix: propagate metadata (behavior & attrs) in _generalevent.py

[pfackeldey]

(Hopefully) fixes #298

Can you give it a try (@jennetd & @lgray) ?

(Hm... It might be more correct to propagate behavior and attrs in each self.multi_layered_listoffset call, but I think it makes no difference here and thus I went with the smaller code change)

[lgray]

there are a few other places where we should propagate attrs as well!

[lgray]

but good catch!

[lgray]

Just taking a look at it, multi_layered_listoffset_input needs the behaviors and such to be set for its assumptions in calling other functions to be met (if I'm reading this right).

So we should probably propagate there as well.

[pfackeldey]

Great, this looks good to me! 👍

[lgray]

The recent changes also fix the problem in the reproducer given.

Will go ahead and merge. I think we're ready for a release after this.