Values are closely related to where they were defined, so
this information should live inside the Value.
This also enables comments to be attached to nested Values.
Change-Id: Ic7481b5a5f26d0ef248d638e2e29252f88154581
An early refactor. Some ideas became clearer as
development continued. Now the various phases are much
clearer and more easily reusable.
Also added a ton of tests!
Change-Id: Ic8f0a70c8222370352e63533b329c40457c0903e