+ Bug fixes based on the optimisations.
+ File required by the unittests.s
+ Unit tests from https://github.com/keleshev/schema/blob/master/test_schema.py converted to unittest instead of pytest.
+ File no longer required - it's part of setupclass.
+ Add schema to rez selftest.
+ Tweak tests to run through rez selftest.
Merge remote-tracking branch 'mark/schema_optimisation_bug_fix' into 2.0