OneOf fields are not contained in the record definition

[Dave Thomas]

Take the example in the repo:

module SampleMessage =
    type test_oneof =
        | First_name of First_name : string
        | Age of Age : int
        | Last_name of Last_name : string

[<CLIMutable>]
type SampleMessage =
    { mutable martId : int option }
    member x.testOneof = x.testOneof

member x.testOneof = x.testOneof should actually be defined as part of the record

[Dave Thomas]

Fixed in #77