Lightning Framework Fake Pull Request

I made this PR to myself so that Ioan/Mark can add comments inline if desired.
Should I just cast it to a RetrieveRepair pointer and check if it is null before using its ``setRepairPlanner`` member function? Would using a ``dynamic_cast`` be safer for error checks? I'm not sure what is best.

I believe it has to be stored as a generic ``Planner`` type because I pass it to ``ParallelPlan`` for threading. I guess I could just cast it then, instead. It does always have to be a RetrieveRepair planner type, yes. Please advise further.