clean shutdown of some codes

[ipelupessy]

Is your feature request related to a problem? Please describe. some codes, especially C++ codes need explcit call to cleanup_code before shutting down (e.g. for cleaning up MPI resources before a MPI_Finalize), this normally done through state model and stop..but this makes a shutdown with out a stop or a del instance unclean, since the del in the codeInterface will not trigger the state model (and thus no call to cleanup_code happens)

Describe the solution you'd like del instance or exiting should always work to cleanup_code if possible (ie if the code is alive)

[stale[bot]]

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