Closes #33.

The regex doesn't actually work, and these urls can be non-standard. We don't really care about these until we're using them, let's let people do weird things here.

And distribute TODOs.

Closes #30.

This is the only place that variables() appears in the definition, and there's really no reason that it would have to be server-specific anyway.

I couldn't stick with the OpenAPI names. This makes much more sense to me. More to come in this area.

This is a list of "string_replacements" objects, which are themselves lists. I want to make sure these stand out as special for a multi-server-with-different-variables situation.