Using processed map in Dijkstra::processed()

[Peter Kovacs]

This ticket is a follow-up of #149.

Now Dijkstra::processed() uses the heap to determine the return value whether or not the current ProcessedMap type is NullMap or not and whether it uses local map or not. It would be nice that the given processed map (_processed) is used if it is not of type NullMap and the heap is used otherwise.

I think it would need some template tricks to implement. Otherwise we could introduce a bool flag that shows whether SetProcessedMap or SetStandardProcessedMap named class parameters were used. But in the the later case extra codes in DijkstraWizard would also be needed, since it does not use the above named class parameters but defining a traits class explicitly.