…t work for my simple code that uses the poisson problem interface. I have not found the root cause. This commit is a quick work-around that instead adds a new parameter max_cells to the pi-DoMUS interface. Such a parameter seems at least as relevant as already existing parameters such as 'kelly threshold' and 'max iterations', so maybe this is actually what we want. This 'work-around' commit violates the concept of 'do not repeat yourself', so I would call this an open issue.

…n't repeat at each time step.