New scope mapper working to some extent.
Minor refactorings.
Refactored reference resolvers back into one class.
Fixed issues with resolution scope mapping.
Can now load meta-schema successfully.
Refactored meta schema.
Fixed recursive constraint validation.
Remove repr dependency.
Implemented resolving readers.
Use URI factory in tests.
Implemented defaulting constraint validator.
Merge branch 'release/0.2.0'