Bug 1256

Carlos suggested this as an enhancement to TAO
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      As many of you know TAO can overflow the stack if you run
sufficiently deep nested event loops.  I'm thinking that we can do a
little better than crashing with a SEGV in those cases.  For example,
we can add a maximum nested event loop depth to the leader followers
loop.  If the depth is reached we can stop all incoming requests by:

1) Queueing them in the fragment re-assembly buffer:  I think all we
   would have to do here is put them in the buffer and not send the
   notification message until the stack depths is low enough.

   This could result in a dead-lock, assuming the application needs
   the request to complete before the stack can unwind, so we may also
   need to:

2) Raise an exception: for example, CORBA::IMP_LIMIT is a perfect
   match, with an appropriate completion status and minor code
   applications can even recover from this sort of thing.
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This seems to be a good solution for the wrteched problem occuring if the 
application tends to create too many nested event loops when doing distributed 
callbacks.