Messed up RoadLanes in some scenarios

[TheDuckCow]

Copying over the unfinished work from #136 , we have some scenarios where RoadLanes don't get placed as they should and as the road textures would imply:

Documenting this as I've needed to summarize it for myself several times, and what I'm planning to do with it:

• A: Two "next" RPs pointing to each other creates two overlapping sets of road lanes
  • Will try to at least skip adding one of the sets of RoadLanes, but tbh it still ends up very screwy because they criss-cross
  • "Normalizing" the container will solve this problem
• B: Two "prior" RPs poing to each other creates a gap (regardless of lane transitions)
  • Nothing we can do about this, since it's one roadpoint which is the parent for RoadLanes that should go in both directions
  • "Normalizing" the road container will solve this
• C: Some scenario where the curves all try to be attached to the "wrong side", even though this is already a "normalized" container
  • I just need to explore this one to find a solution, it's possible it's just messed up data in my test scene that can't be reproduced.
• D: Adding and removing a lane on opposite sides within one segment
  • This is kind of separate to this ticket and more to do with lane matching being off.
  • For now the workaround is to just not do both adding and removing in the same segment, but it would be nice to allow for this since people might want to keep the road lane width consistent
  • Will log as its own bug

As mentioned, half of the items above would be fixed with "normalization" where we go through and see which roadpoints are most commonly in one particular direction, and then flip the direction and connections of all other roadpoitns (physically rotating them 180º) so that everything is now going in order.