GoSuB Browser Progress, pt14

I have a bit of trouble getting the adoption agency algorithm implemented. There is lot of fighting with the borrow checker (nothing changes there), so I have to take it step by step. There are still a lot of moving parts that needs to be implemented, checked and double checked, so this might take a while.

So we're off for a few nights of development work. When I get more tests running, I can try and make sure the parser errors are correct (in both names and locations).