Read or Write only property serialization

Read only and write only properties need to be serialized/deserialized in some cases.

For my current project, I am required to serialize read-only properties and deserialize write-only properties. 

This could either be default behaviour, or opt-in (through the config?), or as an annotation to the property, or both! :smile: 

This PR just demonstrates how it would work if it was the default behaviour.