recursive acceptings leads to stack overflows

[Rune Zedeler]

This time this should be correct.
I found out what leads to my problems.
If you have some sort of recursive accepting context then this little
program

\score { \context Voice \notes { c1 }}

Leads to stack-overflow.
With recursive accepting I mean that either i.e.

StaffGroup accepts StaffGroup

or i.e.

StaffGroup accepts ChoirStaff, ChoirStaff accepts StaffGroup.

Well...
I don't think that this should lead to problems, and I am glad that even
rhough it was my patch that lead to problems then it was no programming
error of mine... Perhaps misunderstanding of what is allowed and how
things work...?

-Rune