unexpected behaviour

[Dietmar Maurer <dietmar maurer-it com>]

I just noticed that ORBit crashes if I raise an user exception in
a method which is declared to raise no exception. This is because
the skeleton call always:

     ORBit_send_system_exception(_ORBIT_send_buffer, ev);

I thing it would be better to do something else than
aborting the program in this situation.

- Dietmar