Generate `path_corner` entities

[victorbstan]

I think we'll have to update the code to generate individual path_corner entities, instead of adding points to a curve inside one path_corner entity... one of the path_corner attributes is wait which is important when a path can be set to wait -1 so that the train stops moving once it reaches that path corner, (or waits, before moving on).

If there are separate corner entities available, then I would move the logic of finding the target path entities into the func train code, to manage it's own movement based on these corner paths

[victorbstan]

On closer inspection, I see individal path corner entities are created, so I will update the train_func script to get data from these path corners and path corner script to save an array of "linked" (through targetnam) path corners instead of just their position in a curve.