title: Making a property deserialize but not serialize with json.net
body: <p>We have some configuration files which were generated by serializing C# objects with Json.net.</p>
  
  <p>We'd like to migrate one property of the serialised class away from being a simple enum property into a class property.</p>
  
  <p>One easy way to do this, would be to leave the old enum property on the class, and arrange for Json.net to read this property when we load the config, but not to save it again when we next serialize the object.   We'll deal with generating the new class from the old enum separately.</p>
  
  <p>Is there any simple way to mark (e.g. with attributes) a property of a C# object, so that Json.net will ignore it ONLY when serializing, but attend to it when deserializing?</p>