• Improve vessel.maneuver.add and vessel.maneuver.add_burn_vector to use the
  correct orbit patch in case multiple maneuvers are planed ahead.
• Add vessel.maneuver.remove_all() helper to remove all maneuver nodes at once
• Add vessel.trajectory field containing all the orbit patches of the current
  trajectory of the vessel (i.e. where the vessel will end up if it stays on its
  current course without intervention).
• Add vessel.maneuver.trajectory field containing all the orbit patches if all
  maneuvers are successfully executed.
  • This list will always start after the first maneuver node. I.e. if there are
    no planed maneuvers it will be empty.
• Add orbit.start_transition and orbit.end_transition fields representing the
  patch transition at the start and end.
• Add orbit.previous_patch and orbit.next_patch fields (both Option<Orbit>)
  to get the previous/next patch if available.