Cure performance bug of ref-heavy, self-contained schema

[fge]

Schema here:

https://gist.github.com/jimklo/5416348/raw/bf17eea14c35996ff1293c75a88c9224bb4e8a77/lrmi.json

This 700+k schema (!) makes very heavy use of "JSON Pointer only" JSON references. Any validation against this schema takes nearly a minute, which is too much.

The first plan is to try and expand all refs in such a schema (and check the schema syntax). In the final validator build, it can then be decided whether the full, existing mechanism is used, or a simplified one with an already expanded schema.

[fge]

Too late for 1.2.x.

Will be fixed for 2.0.x.