Cross branch paths aren't a sensible dv

[davidhyman]

Going from Duna -> Jool, one is routed through Kerbin's SOI.

This also applies to the child planets e.g. Laythe -> Pol (currently it takes us back to a highly elliptical Jool capture orbit).

Once the SOI is at the same depth in the hierarchy (relative to Kerbol) we should transfer directly to an interception in the other SOI.

Can this be solved using just dv averages and a smattering of extra edges on the graph? Or should I be doing something entirely different? (see https://github.com/alexmoon/ksp)

[davidhyman]

Fixed in #5