Two neXtSIMs running concurrently

[einola]

To run a global model setup consisting of one ocean and/or atmosphere model and two neXtSIM models, we must ensure we can have two neXtSIMs running concurrently.

We need to scope out the requirements for this. An initial list follows.

• All log files need to contain a unique identifier or be written to a unique location
• All output files need to contain a unique identifier or be written to a unique location