Adding a `world` module for dependencies of only `World`
Renaming "WorldLinks" => "SortedLinks"
Cleaning up `World` a bit
Moving `World`'s link-related stuff into a `LinkManager`
Narrowing `World`'s public interface a bit
Trimming down the public interface of `LinkManager`
Minor comment/type annotation tweak
Removing false comment
Separating out optimization-related variables
Moving turtle-related stuff from `World` to new `TurtleManager`
Cleaning up `World`'s imports

For some reason, I view this as a huge victory