Load Rip::Core::System last
Remove stubbed in implementation of System.String.@.{downcase,upcase}
Attach List class to System.List
Refactor Rip::Core::Base.define_class_instance to optionally load class defined in Rip
Implement Rip::Core::Object.class_instance

TODO Needs tests
Interpret ancestor classes
Override Rip::Core::String#ancestors to inherit System.String from System.List
Refactor Rip::Core::{Base,Prototype}#[] to account for class ancestors
Stop inheriting System.List from System.Enumerable (for now)
Use Rip source to define System.{List,String}
Attach String class to System.String
Stub in commented implementation for System.@.{lowercase,uppercase} (Rip source)
Stub in commented class properties for System
Implement System.require to load external via Rip::Loaders::FileSystem

Also notable...

* Define System.List (in Rip)
* Define System.String (inherits from System.List in Rip)