Fix delta-v stats for 0.90

In editor no FuelLine part is reported anymore. It is now a CompoundPart. Private members contain the actual fuelline element, as I could not access it I consider the fuelCrossfeed attribute to distinguish it from a strut.

Also 2 minor changes for advanced transfer: do not throw exceptions in nominal conditions and remove the minimum time before the node (it might be half an orbit in the past, but allows recomputation of the node minutes before the burn).