Version 0.12

• #56: Add JsonUnionEncoding.UnwrapRecordCases, which implies JsonUnionEncoding.NamedFields and encodes union cases containing a single record field as if the record's fields were the union's fields instead. For example:

  type U =
      | U of r: {| x: int; y: bool |}
  
  U {| x = 1; y = true |}
  // Serialized as: {"Case":"U","Fields":{"x":1,"y":true}}
  // Instead of:    {"Case":"U","Fields":{"r":{"x":1,"y":true}}}

  This option is compatible with all union formats (AdjacentTag, ExternalTag, InternalTag and Untagged).
• #64: Fix serialization of unit as field of an F# type. Thanks @NickDarvey!