Wren now has three classes of modules:
- The one magic "core" module that's built in and always needed.
- Auxiliary libraries like "meta" and "random". These do not have any
dependencies, so can be used even when you embed Wren inside an
application. But they're also optional and can be disabled if you
don't need them.
- CLI modules. These ones need libuv and are tied to the CLI wrapper
around the VM.
