Integrate the duplicate generation for LMST into the generated code

[davidgiessing]

As the LMST algorithm is fairly sensitive to the direction in which it observes edges it is necessary to have inverted duplicates of every edge that is not directly attached to the this node. The duplicates should be generated at runtime before LMST is executed. They will then be attached to the neighbor list. They need to be removed after executing LMST.