Fine-tune schema generation

[bdarcus]

Premature, but at some point, if this goes anywhere, we'll need to include id properties on the schemas, set some definitions to be extensible, etc.

https://github.com/YousefED/typescript-json-schema#command-line

Also see API docs, for additional annotations, including formats and examples.

https://github.com/YousefED/typescript-json-schema/blob/master/api.md#annotation-tjs

Also, compare to:

https://github.com/vega/ts-json-schema-generator

Both create pretty verbose schemas, which I haven't figure out how to reign in.