Develop and implement logic for reconfiguration of timeslices

[danielru]

Upon convergence, a timeslice object should be reconfigured to iterate on a later timeslice. Need to modify

• start time
• end time
• initial value
• neighbours
• reset residual and iteration counter

For now, do not consider the case where e.g. different time steps are to be used. The reconfiguration should avoid reallocating buffers for the solution?