Incorporate a Lambert solver and coupled optimization algorithm to find optimal body-to-body transfers without having to resort to using a circular, coplanar orbits assumption.

Do the following:

-Select 10-50 points along the next n revolutions of the body you are orbiting (where n is use-defined).
-At each of the points, start an optimization algorithm that ties in with a Lambert solver to compute delta-V required to go to the target body. The variable the optimizer alters is the epoch of the delta-V maneuver, and varying this varies where along the orbit the burn takes place. Multiple points along an orbit are selected in order to avoid getting stuck in a local minimum.
-Turn the delta-V into a maneuver node and have MechJeb or the user execute.

This is Arrowstar from the KSP forums, hit me up via PM if you have questions. I've written a few Lambert solvers before and they aren't too hard. I have a nice one coded up in Java if you feel like porting it. The optimization package will probably have to come from a 3rd party, open source repo or something. :)