Update schematics

* schematics 0.6.0 is not able to validate models holding dictionaries with keys including . or $
* current version is already 0.9-4

**Note** that the models of schematics 0.9-4 are not compatible with the models of schematics 0.6.0, so this will be a non backwards-compatible change for most projects using supercell, so maybe we need a new (beta) major version for this.