Added some tests based on J. Garriss' 5-level JSON schema.

Test test_json5_3 fails because whitespace is not being made optional. This JSON doesn't parse "[null,null]", but does parse "[ null , null ]".

It seems to take a very long time to parse these tiny examples, or possibly to compile the schema, but the schema isn't very big.

tests test_json5_1 and test_json5_2 also show the slow speed.