Add YAML serialization backend definitions.
Minor whitespace cleanup.
Add YAML serialization for base_strings.
Add YAML serialization for some basic collections.

That's a /lot/ of boilerplate, because I can't get template template
parameters working. It should be a lot easier.
Add run support for YAML configuration.
Switch __patch function to take a string.
Add types to patchables state.
Add YAML definitions for records.
Add YAML definitions for collections.
Add YAML definitions for __global_context.