trying to do pocketing

DanielFalck from #cam has found where to edit the start point, so we hope to do pocketing.
In this example, I simply made a cuboid 20x20x20. In CoreRoughGeneration::FindGoStart(), I changed a0 and a1 to be
P2 a0(10.0, 10.0);
P2 a1(12.0, 10.0);
This is this result ( click on picture ). It looks like the algorithm doesn't car if it goes outside the boundary, so long as everything inside the boundary is cleared.