A correct MPI program should do that.
As MPI_Finalize is part of the destructor of MainObject we need to
make sure that it's destructor is called before the return statement.
We do that manually by resetting the unique_ptr that we now use to
store the MainObject,
Instead of unconditionally issuing MPI_Abort if we encounter a fatal
exception, we try to test whether all processes have experienced this
exception and if this is the case just terminate nomally with a exit
code that signals an error. We still use MPI_Abort if not all
processes get an exception as this is the only way to make sure that
the program aborts.
This approach also works around issues in some MPI implementations
that might not correctly return the error.
Multiple messages like this are gone now:
```
--------------------------------------------------------------------------
MPI_ABORT was invoked on rank 1 in communicator MPI_COMM_WORLD
with errorcode 1.
NOTE: invoking MPI_ABORT causes Open MPI to kill all MPI processes.
You may or may not see output from other processes, depending on
exactly when Open MPI kills them.
--------------------------------------------------------------------------
[smaug.dr-blatt.de:129359] 1 more process has sent help message help-mpi-api.txt / mpi-abort
[smaug.dr-blatt.de:129359] Set MCA parameter "orte_base_help_aggregate" to 0 to see all help / error messages
```
Bu we still see something like this:
```
--------------------------------------------------------------------------
Primary job terminated normally, but 1 process returned
a non-zero exit code. Per user-direction, the job has been aborted.
--------------------------------------------------------------------------
--------------------------------------------------------------------------
mpirun detected that one or more processes exited with non-zero status, thus causing
the job to be terminated. The first process to do so was:
Process name: [[35057,1],0]
Exit code: 1
--------------------------------------------------------------------------
```
In preparation of adding support for opening/creating wells or
groups in the middle of a report step. This is needed if an
ACTIONX block runs something like WELOPEN or WELSPECS/COMPDAT.
