Reliable destruction

[Pierre-Eric.Melchy at uni-konstanz.de]

Hello Benjamin,

What would happen if an exception was thrown in the middle of setup()?
tearDown could not handle this case without having a list of the
objects already constructed (Or I would have to rely on the automatic
call to __del__, if it is reliable).


There is still some problem:
Imagine a communication error in run() which would cause del to fail on
the instrument.
Anyway, I think this case is still more difficult to handle.