* Add OpenAPIRenderer and generate_schema command
* Add both OpenAPIRenderer and JSONOpenAPIRenderer
* Add flags to generate_schema command
* Fix syntax error
* Pull coreschema references into method, so they are only used if 'OpenAPIRenderer' is in use.
* generate_schema -> generateschema, and fix to OpenAPIRenderer
* Ensure that renderers generate bytes and generateschema outputs text
* Drop unused import
